Oh yes, it's a good idea for preservation purposes! Lots of fandom classics have vanished for one reason or another. And a lot of people are re-readers with favorites they go to, so I know many people have set up procedures for saving and retrieval.

I technically do have some works saved but it's maybe 30-40 after 20 years. And I have never re-read any of them, I just thought I might want to. There's always such a long queue of new stuff that I know I'm very unlikely to go back to anything.