I think it's partly a problem of scale.

When you become a target of abuse - or mass criticism or what have you - you're dealing with hundreds or thousands or higher orders of tweets to deal with.

Often more than enough to drown out the positive, because detractors are so often more vocal than supporters.

That can be very flustering on a site with a small linear feed. Individually blocking people doesn't scale.

Block lists kind of help but they're a brute force solution and we can all see the problems and edge cases from that solution.

It's cynical, but perhaps there is a market opportunity there.

It just seems strange that Twitter hasn't come up with something significant in that vein.