Partridge Family was all for show and other than a tambourine or cowbell here and there, did not play any instruments at all. But David Cassidy did have some real vocal talents and as you probably know, went on to have a significant solo career with a few Top 40 hits.
Interesting trivia about Partridge Family, the TV show they ended up starring in was actually inspired by an actual family band called The Cowsills. Now the Cowsills were a genuine band with three Top 10 smashes under their belts before the TV show based on them was created.
But alas, The Cowsill family were not considered "telegenic" enough for a national TV show. So the Partridge Family as we know them today was assembled from scratch and musical talent was not required as all their songs were recorded by session musicians (with Shirley and David providing some real vocals).
As for the classic rock bands you mentioned, yes, I know and appreciate all of them. It's hard to pick favorites from all those diverse artists but I guess I should mention Bob Dylan, Elvis Costello, Emmylou Harris, Fleetwood Mac, Rickie Lee Jones, Linda Ronstadt, Pink Floyd and Rolling Stones who have put out consistently high quality music over a very long period of time (many of those mentioned are still active today).
I knew that, but their music on the show was still pretty much bubblegum to me.