Am I really smart or really stupid?

Not a bad theory, but you might be missing important points.

The phono preamp needs to amplify the small signal from the cartridge. The quality of the amplification circuits should not be taken for granted. I have seen 'philes comment that these circuits have been improved over the years, just as preamps and power amps have improved (arguable, but generally accepted) over the years. After getting right the reproduction of the frequency range, there are things like macrodynamics, microdynamics, imaging, etc.

I don't know how much this should cost. Obviously, a high volume product could provide a better value.

Other factors that enhance modern phono preamp offerings include load and capacitance matching, a la the Manley Steelhead (as well as numerous other units). Of course, this adds to the cost, as well as the attractiveness, of the phono preamp.

Your proposed setup with the Yamaha might sound just fine. If you like it, then you're done. However, you might consider auditioning a more expensive modern phono preamp in your system just to make sure you're not missing something.

To answer your question, please forgive me for saying that I don't think you are really smart. I also don't think you are stupid, just a little ignorant at this stage of your audio development. More importantly, I hope you are lucky with your Yamaha and you have a good match.

The part about it shouldn't cost $3000 is well taken. I don't know how to put it...designers of circuits who throw more and more money at them to make them better are not innovaters at all. If you have the money to buy really expensive gear, that's great. The Sutherland PHD phono preamp, which I have never heard and never will, boasts about its circuit that looks for a signal every 30 minutes and turns itself off if it doesn't find. I think it's a great concept. But the ads say how it preserves battery life and they're only a buck apiece (times 18) to replace. As though the person who has the 3k to spend on it would care. I realize that this post does not have much coherence to it.

Nothing new here. Been doing it for many years as I'm sure have many others. The quality of the phono stages does vary wildly and your Yamaha's is highly average. Some killer phono stages in older preamps on the cheap are the NAD 1020, Apt Holman preamp, B&K Pro 10, Adcom GFP565 to name a few. These will all stomp your Yamaha.

Nothing wrong with doing as you suggest. However, it must be noted that on those old preamps, they probably need some refurbishing, and at least re-capping, to sound anywhere near like they did when they were new. Some of the internal components degrade with age and use, and need to be replaced to approximate original performance.

I might say that an old Yamaha C2 is not giving you anywhere near what is possible today with phono preamps. But it will do the job well enough for you to have some listening enjoyment until you discover what else can do better for you.