Interesting observation, Alexis. No doubt you're right. I have never forgiven disco because it came out and ruined
my life, which had been filled with all those guitar-oriented songs which I just loved. I think the move away from guitars started in the 70s and ... wait, wait, and idea is forming here ... perhaps that's one of the reasons why the Beatles as solo artists had such a hard time making the transition. The instrumentation and style had changed away from their core strength.
I mean, there were kids at my school who actually liked
disco, who played it and listened to it. Compared to all the wonderful artists out there! You could have CSNY, and they would play some repetitive stupid thing with 3 notes and one phrase and they liked
it! (You can see how this has scarred me for life.) But I bet those kids would also have said "that's so old school, it's like for my parents". (or older sister/brother)
Now, to DaveRam's point, there is a whole other aspect to the Beatles remaining "contemporary", and I think it's the strength of the songs and music. Yeah, it might sound old, or not modern, but it's still good
. The young listeners the band continues to acquire to this day proves that. So there is something transcendent about the music, the way people can still enjoy that raucous noise that young hotshot Mozart produced. Yeah, it sounds a little dated now... but it's still good.