Possibly an unpopular opinion, but I don't think Lemmy should be viewed as "spite sites". If the entire focus of the community here is to point and laugh at Reddit's failures, rather than actually provide an adequate site's worth of unique content, people will quickly get tired of it and leave.
Of course, it's the hot topic at the moment so it's understandable, but I hope we'll move away from it at some point.
I heard mention of it occasionally, but that was also years after the initial move from Digg, so I can't comment on what it was like first hand during the initial move time.
However, I don't think anyone viewed Reddit as a "spite site" for Digg, Reddit was around for years and was semi-popular before Digg committed suicide. It was simply the natural move.
Lemmy on the other hand has been around for a little bit, since 2019 as far as I can tell, but a rather minimal userbase.
Certainly if we get to the point where Lemmy (and its current userbase at minimum) sticks around for a few more years, it'll likely largely move past the whole Reddit fiasco. But it also needs a large variety of non-reddit-related content to interest users, otherwise this site will likely die before it gets there.
I mean they keep doing stupid shit so there's still stuff to talk about but look around, dude. There's lots and lots of active conversation that has nothing to do with Reddit.
There are plenty of communities where reddit doesn't really get discussed but on the catch-all/meme places, it's a topical thing right now so we'll definitely be seeing it for a while yet.