For me, I've found POSSE to Twitter and Mastodon using RSS and IFTTT-like services has been a relatively low-effort thing to do. The downside though is any follow-up conversations take place on those platforms. That hasn't been an issue for me yet though so until it is, I'll continue to use my relatively low-effort solution.
I agree with you on likes / reposts. My current implementation of those posts is focused on Webmentions, which means it's virtually meaningless since few people know about let alone integrate Webmentions into their website. I would argue replies tend to fall into that same space as well. I have however found great use in bookmark posts to which I try and add some content from the source document to help me quickly identfy why I thought that post / website was interesting or relevant to a specific topic at that time.