Sometimes what I’m interested in may be more specific or niche, but a lot of search engines and filtering systems don’t seem to provide a way to drill down to those results. What may be some reasons behind that?
Or am I overlooking some obvious ways to search/filter this way?
That requires turning every read into a write – which is slow/expensive generally. (That might not matter much for Google – who try to record everything you ever do already, basically – but it matters for everyone else.)
Also, it tends to promote spam and offensive niche content. kbin’s got a sidebar that tries to promote random low activity communities and posts, for example, and it’s almost uncanny how much crap it pushes up…