With boost on reddit I would just block any subreddits that I felt was just noise. Any American centered subreddits (mostly politics), NSFW subreddits (back when those showed up in r/all), niche meme stuff like that deep fried stuff, etc... You could also block keywords like "elon" and "trump". It actually made r/all a decent experience to browse through.

If it isn't already a feature on lemmy, hopefully it will soon. I much prefer letting the user do the filtering than the nuclear option that is defederating. Boost for lemmy is also on the way so I expect that to be an option once the app launches.