Different subwoofer settings for different albums?

So a dealer I know told me that he doesn’t use subwoofers and doesn’t know anyone who does (!) because he finds that every record has different levels of bass and would require a new subwoofer crossover point to properly blend with the main speakers.

A new crossover point; no, a different amount of gain; maybe. Considering that the acoustic properties of your room differ from those of the recording and mastering venues not to mention the amount of contraband in use at the time, it is possible that the balance between mids and lows could be off, but it is rare. Usually it is just a few stray frequencies that are off that muck things up.