So how can a great system solve less than great recordings

I dunno. How?
Your statement reveals nothing.

Which is why "audiophiles" get siloed into listening to sonic spectaculars. On most boards I participated in, I usually put up a thread called "Non-Audiophile Records" to discuss standard issue pressings from back in the day. 
I take the good with the bad. I'm not a Stones fan, but the early UK boxed label (stereo) is a decent sounding record to these ears, though I haven't listened to it in quite a while.
Ditto, the UK first press of All Things Must Pass has some body and dimension that is sorely lacking from the US copies (bought one of those when it first came out). 
Which takes us into the thicket of finding desirable pressings of records, a subject that is bottomless. 
I find lots to listen to; at the moment, "used" record prices are inflated and desirable or rare records are more expensive than ever. 
My sweet spot, musically, for the last 4 or 5 years has been so-called "spiritual" or "soul" jazz from the early '70s-- that stuff has gotten astronomically priced and many have never been reissued. 
It's fun to find a killer obscurity, especially if it's not on everybody's radar. 
But, there are some records that just sound lousy and if you like the music, you focus on that, not the sonic demerits. 
I used to keep a shelf of known impressive sounding records for demo purposes. I gave that up a while ago-- I just listen to what stirs me and buy what I can, notwithstanding the market. 

OP, if you tune your system to a very high state of tune, you can get to the point where only a handful of recordings sound good. Been there done that. The best tune in my opinion is when only a handful of recordings sound BAD. Work towards making everything sound good even if you loose a little detail or shimmer. 

Agreed @russ69.Nothing wrong with a high fidelity system that is also a bit forgiving of less than stellar recordings. The best recordings will still sound fabulous and the Stones albums will be listenable, fun,and satisfying.

Artemus_5

Actually, it is not condescending but right. Yes its about making the music sound better. But, The music sounds best when it is brought forth in the purest of signal from the source material. This was the goal of high fidelity., to be faithful to the music as recorded. That means not adding or subtracting anything to/from it. Adding things to make it sound better, IE tone controls, is often a band aid to fix something in the signal.

Thank you. And well said.

FWIW, I have found that as my system gets better, my music also sound better. Of course there are some which don’t sound as good as others.

Indeed. One thing that really stands out is the way every single record I have sounds so much better now than I ever imagined.

There are several records I always thought were pretty good, but too laid back, reserved, pallid. All three Linda Ronstadt/Nelson Riddle for example, it was like her voice was fine but the orchestra was very background and all the solo sax or whatever was barely there. Now it is just incredible, the orchestra is big and present and detailed, and the sax leaps out in full glory. At the other extreme, Nilsson Schmilsson used to feel a bit edgy and hyped. Now it is just crazy liquid detailed smooth and natural.

One would think anything that "fixed" the reserved Ronstadt would be too much and wreck the Nilsson, but that is not the case. Not at all.

It is one of the more puzzling things, how every recording now is not just different than the others, it is more like it is in its own world. So very different it is hard to believe. I have quite honestly never heard anything like this anywhere else. This I think comes from being genuinely revealing of what is hiding deep down, and not adding anything in the process.

I have a pretty good idea why this is. Frank I am sure has a pretty good idea too. And Krissy, of course. Thank you, my dear. It has nothing to do with being condescending. It is more like, please come swimming, the water’s fine, and oh by the way here is how to not get any up your nose.