Exactly, truly appreciating art, or an artist requires coming across one or more pieces that really resonate with you (which is really a function of what's going on in your life, state of mind, mood, sensitivity, and general ability to engage with art, and in some cases understanding its historical context, within the art community and in the broader world).

Once that happens though it opens the door to appreciating other pieces.

I have experienced that same phenomenon with bands, where people say "X" is great and I hear a song and don't "get it" until I find some other song by them years later and it all sort of "clicks" in a way it originally didn't.

With that said, there are definitely people that try to say "I like X" to fit in. I just don't know about the 50% bit in the OP, but then again, 90% of statistics are made up.

BTW -- The Old Guitarist is on permanent display at the Art Institute of Chicago. It is wonderful in person if you haven't been yet.