The question is, where's the line that crosses into getting too personal? Criticism of someone's views is fine, criticism of their actions is fine (though people tend to slip into worse while conducting it), criticism of personality traits starts to be a different story.

This is not a binary thing. I can see good aspects to the kind of discussion you were starting there—I just think the bad aspects outweigh the good.

A lot of this is about the difference between personal conversation and online conversation. One can have a fun and harmless personal conversation about this kind of thing with friends, but the same thing broadcasted to thousands of strangers (and other commenters) online leads to different dynamics, a lot of which get pretty ugly and are best nipped in the bud.