I have lots of thoughts on this one. I totally agree that the amount of junk out there is on the increase. One of the reason I like Reddit/Lemmy is to crowd source the findings for worthwhile content. I think the secret is being selective of what you subscribe to. I also use reeder by Readwise and let it summarize using AI anything I throw its way. I then use the summary to decide if I even want to read the full content. I’m staring to pay more attention to platforms like Substack and paying for content. In general the problem you highlight is one that I think AI can’t help greatly in fixing. Maybe an AI that knows you and can pre read something and tell you if you should even bother.
I have never understood why people would like Lemmy and then look at any feed other than subscribed. You might as well use mastodon if just a free flow of posts is your thing. I do like the list of keywords though for those rare occasions I look at the universal feed.