So far, I have only blocked those distributing spam via my response sections. I typically follow through to their profile to verify that it is indeed a spammer. Then I report them to Medium and block them at the same time.

I was once tempted to block someone who only made rude comments, but then I refrained from blocking that person. The readers of my articles and comments will form their own impression of the "offender", so why should I protect him by hiding his true character from plain sight.