Honest question about cartridge vs. turntable performance.

 if there is surface noise when playing back vinyl (even after thorough cleaning) isn’t upgrading the table a nearly useless endeavor beyond a certain point since the noise floor improvement from a better table will never be realized?

not necessarily. you would have to do some testing to refine what is causing the noise. surface noise might be a few different things. the best approach is to first eliminate the obvious things before you start thinking about the platter or motor.

ideally you have a few Lp's and could hear them on a known properly performing turntable to get a reference for how they should sound. maybe even take them to a local hifi shop and ask them to play a short passage to find out (assuming they have a turntable).

or buy a new record that you confidently feel is likely quiet and properly pressed.

1--this noise could be as simple as some sort of gunk adhering to your stylus. heat from friction in the groove can cause that gunk to stick strongly. read up on proper cleaning methods for your cartridge.

2---could be the vinyl itself maybe with groove damage. or just a terrible pressing.

3---could be a loose cartridge mounting, or loose arm mounting.

4.---obvious noise from the platter or motor is unusual. typically you might hear some noise during very quiet passages, or maybe some 'sour' discontinuity during horn or piano sustains. but both of those things are lower level type noise, not in your face. 

With groove damage, the issue is not obvious in most cases by looking at the LP. Last night, I put on what looked like a Mint condition Direct to Disc, the groove noise was annoying from the lead in groove on the first side to the lead out groove on the last. 
Many LP's look to be in great condition, but once on the table, they show off their true condition. I think in the case of this particular LP, the previous owner(s) had used a cartridge that was worn or otherwise damaged, as such after just probably one play, the LP was damaged. The fact that the LP was a Direct Disc would lead me to question whether the album had been also played back on gear that was unable to really track this album..thereby resulting in the damage.

@millercarbon  I totally disagree concerning the demotion of digital sound to analog sound.  They are different but not incompatibly inferior to one another.  My CD reproduction has the same (or better) PRAT, tonality and dynamics as my analog reproduction.  The analog has the extra breath of life.  Analog can also have many problems from the vinyl pressing.  The biggest difference is mastering and either one can have great or not so great mastering.  I used to do all my semi-professional recordings on R2R, then DAT, now on a digital recorder.  I know the difference is there but there exists an advantage to each type.

As to turntable/arm/phone stage/cartridge-My modded $1100 1989 purchase of an SME IV arm sold last year new retail at $4600.  My phono stage would cost over $10K today (I paid $1500 20 years ago).  The Audio Interface SUT is now again available directly from Jensen transformers at the same price.  My turntable is a VPI TNT VI and would cost at least as much as I paid to replace it, if not more.  Only the cartridge is expendable and I chose to pay $2K 14 years ago.  Now I'm looking at $3K to $3.5K.  I am not willing to spend more even though I can afford a more expensive cartridge.  I like my tonearm because it is so durable and VTA is not as critical per LP as some other high end arms.  

Here is why it is a bad question to ask which is more important, turntable or cartridge. Think of a small jazz combo comprising 4 or 5 instruments and players. In such a group, the drum, bass, and/or piano can be thought of as the rhythm section. Most often, the rhythm is carried by the drummer or bassist. The turntable is analogous to a rhythm section. It alone determines the musical pace or tempo. The turntable's job first and foremost is to move the LP past the stylus at a constant speed regardless of forces that would tend to momentarily slow the platter. If the drummer is not keeping good time, the music will sound "off", too fast, too slow, dull, regardless of what the lead player in the group is doing. An experienced listener can hear it. Same goes for a turntable that is incapable of maintaining a constant speed. Think of that as time, t, on the X-axis. The linear progression of the music depends upon the turntable. The cartridge works in concert with the tonearm to pick up and accurately represent the signal encoded in the LP grooves. The work of the cartridge/tonearm is analogous to that of the soloist who heads up the jazz combo. His musicianship can be impeccable and original in content, but if the rhythm section is "off", you feel it. The cartridge/tonearm are responsible for amplitude, which is manifest as voltage at given frequencies, the y-axis. I’ve already mentioned that all my experience tells me the cartridge and tonearm should be thought of as a unit, a closed system. No matter how accurate the cartridge and tonearm are at translating changes in signal V, the music will not sound "right" to an experienced listener unless the turntable does its job of maintaining perfect timing, t, by driving the LP past the stylus tip at a constant speed. Yes, turntables sound different from one another, even two turntables that both keep good time will sound different. This is due to noise or the suppression of noise, either from the motor or the bearing or elements of the drive system, that separate one turntable from another, and to the turntable's capacity to control and dissipate various resonances. This is why I say that turntables do have a "character" that stays constant regardless of what tonearm and cartridge are mounted on it.  The cartridge and the tonearm are doing two entirely different things.

"if there is surface noise when playing back vinyl (even after thorough cleaning) isn’t upgrading the table a nearly useless endeavor beyond a certain point since the noise floor improvement from a better table will never be realized? Am I being accurate in my assessment?"

To the OP:

No, I do not think you're being accurate in your assessment. 

I've owned the same turntable for 35 years, a Michell Gyrodec. In recent years I've made non OEM changes to both the main bearing and the suspension which have resulted in fairly significant decreases in surface noise. 

Obviously, it's very difficult to quantify whether those reductions in noise were less or more than those achieved with changes to cartridge, phono preamp, optimizing cartridge/tonearm matching, optimizing the cartridge/phono preamp interface etc. all of which can result in fairly serious reductions in surface noise (along with clean records of course).

For what it's worth, the Ortofon 2M Black does seem to have a bit of a reputation for accentuating surface noise and also being demanding of setup. So setup alone may ameliorate some of your issues with noise.

That being said, the 2M Black does have a pretty good reputation. If it's in good condition it would be the last thing I would change. I think your funds would be best served improving the table (and arm with a view to optimizing with the 2M Black and possible future cartridges) and possibly your phono preamp, which I don't recall being mentioned in this thread-perhaps I've missed it. 

You should reap significant improvements/gains with a table/arm upgrade and not just in the surface noise department. The phono stage may need attention too. Unfortunately, analog is the sum of its parts-all of them are important.