Ever since I've started using mastodon, where users can filter accounts, whole domains, and posts containing keywords, I wished every site with user-submitted content would allow you to do that.
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
For as long as I've been on Twitter it's always been super easy to block keywords, accounts, adjacently related topics, etc.
Anyway, I wholeheartedly agree with your underlying point that users should be allowed to curate their experience with a platform.
You can-ish. At least on old reddit's /r/all page. There's a block list you can curate for yourself (when logged in) on the right hand sidebar. Sadly, it doesn't work for "popular". The filter list does carry over to the new interface, FWIW.
"Displaying content from /r/all, except the following subreddits:"
Love this site - the breadth of knowledge and willingness to share it is so refreshing.