I'm assuming that "spam" is largely either @spam or follow-spam. Also, I suspect that blocking @mention after @mention gets a little old after a while.

I get almost a dozen spam mentions or mentions directed at a misspelled username everyday. That adds a lot of overhead to my usage that get old to the point where I don't even want to read my mentions steam anymore. Certainly less frequently than I used to.

> Also, you don't get @mention notifications if you don't follow them

Most of the people I follow on Twitter I found in this way. An echo chamber is not what I go to Twitter for.