I do like the distinguishing factor between marking a commenter and blocking. I don't like (and think it's dangerous) to feel like blocking any old bad commenter over one comment is the go-to option, so having a way to self-warn myself if this is the same user before going nuclear is a nice touch.
>The main problem I have with this is that I can no longer flag or rebuff their posts (whichever may apply), so these people become the proverbial "missing stairs" if everyone starts doing it :-/
True, it is indeed a macro issue. But at the same time I feel it's a micro problem and there's a point where I need to look out for myself as opposed to the site at large. Let sleeping dogs lie, for now.