So how can a great system solve less than great recordings

Without having to change components, cables are often used to balance the highly-resolving-system vs. poor-recording dilemma.

Although many people are using cables to realize the full potential of their equipment, they are often used to find a balance. Hopefully this simple statement won't start a cable-war dialog; not intending that!

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.