Imgur, for instance, lets me filter in and out loads of specific tags from my feed (also specific use posts).

It's relevant to note that Imgur doesn't have a communities/subreddits equivalent. Images are the rough equivalent of a post, and tags are the closest they get to communities. I'm quite certain that there are tags for both Art and Drawing, and following the Art tag doesn't mean that you won't miss out on posts that are tagged as a Drawing and not as Art. The result is really not that different than Lemmy, you still have to discover all the different tags you want to follow.

Not to be flippant about your tag examples, but those exact communities already exist (edit: ok, admittedly the search for art returns a bunch of unrelated junk):

• https://lemmyverse.net/communities?query=%22Science%22
• https://lemmyverse.net/communities?query=gaming

Now, of course... those are not the only communities addressing those topics. There's retrogaming as a subset of games, there's photographyas a subset of art, etc. But as previously noted, that's true of tags as well.

A whitelist based subscription method DOES work, and is implicitly what everyone uses on very large community sites like reddit and also very large tag-based sites like Twitter/imgur. Of course you miss out on some stuff, but when you find something you're missing... you add it to your list. It's ok not to find every last post you care about and doing so is an impossibility.