My mother was in a dementia specialist home for nearly 8 years. They did play a lot of old songs, and ditto at singalongs, but it's a bit different where dementia is concerned, since memories are progressively lost, newest first. So old songs were often the ones that were best remembered, and everyone always seemed to enjoy them. In most of the residents dementia was well past the early stages and I never heard anyone complain about the choice of songs.
They also sometimes played a game of 'musical bingo' where they played snatches of very well known old songs/hymns, and they filled in large bingo cards as they recognised them - often with a bit of help.
I don't know about anybody else, but although I grew up in the 60s, I like the old songs, too, and will sing along to 'Daisy, Daisy...'. Or 'My old man said follow the van...' with the best of them.