So how can a great system solve less than great recordings

Before I get chewed out for my cable comment, I will acknowledge that many people avoid some of the higher-resolving brands due to this issue, or are careful how they pair electronics and speakers where one or more components are highly resolving. If this doesn't work to the degree desired, then making adjustments with cables is one way to go. I don't see this as a tone control; more of a fidelity control (musical/resolving balance).

A great system will only show the flaws of bad recordings more but that is only a problem if all you listen to are inferior recordings the search for great sound in a system is findings the great recordings to play on it and enjoy them and there are a lot of great records out there.

For me, the saddest part was when I realized that "older recordings" in the OP meant 70's and 80's. My first scan had me thinking that 70's and 80's were fine, but "older" recordings not so much. I guess "older" is relative.

Always look on the bright side of life. Recordings are works of art. Each one is different. Why not take pleasure in discovering as much as possible about each one?  That’s what music lovers do. 

As usual, millercarbon takes the cake! I often look at the threads to read his replies :)
Well, the question was quite ambiguous, as something very different was implied by the title of the post and the explanation (main text body of the question).
I'l try to reply to both.So, a good recording is always a good recording regardless of age. Reissues / remasters can give wider access - ie provide more copies so you can buy, as there is only so many (so few) originals in circulation. My experience with half speed remasters, 180g special pressings etc - they NEVER even came close to the originals. I compared about 5 special reissues to the originals I have in my collection, and in every single case the original pressing won by a huge margin. That being said, having the special remaster is a million times better than not having anything. Yet, all a reissue can do, is to have the least possible loss vs the original early pressings.
As to the title of the question: how can a great system resolve less than great recordings? Well, will less than great results.

However, a great recording does not equal modern recording. In the 50s there were plenty of great recordings. Yet, a good number of ultra-high end systems today cannot do justice on them, as they are most often voiced to match only a very specific kind of recording procedure. (Overspecialization, it's the most common feature of our age in every area.)
Maybe you were wondering what kind of system can read out the most of a recording, even if that was not the most perfect recording ever....