I think you might be on to something, if you're saying that a personal or tonal response might be necessary to certain articles. Someone earlier mentioned the Ethos, Pathos and Logos vectors for disagreement, which I love. I read what you're saying as that just because an attack is on the person, doesn't mean it's irrelevant, which I think might be true. This means that there's different targets here and qualities of argument on each target. I've got a comment somewhere on adding dimensions to these levels and splitting them out, although the examples I gave can be improved on I'm sure.
I think it's fair to say that most name calling on the internet is of a low level variety, hence why it might get munged into a single list like this and placed at a low level, however a personal attack may take a higher and more-legitimate form, although I've not come to any examples of that.
There is a question on the legitimacy of arguing against anything other than the actual logic of the argument - I'll leave that to others to work out, I'm happy to say that there are different lines to attack on, and different qualities of attack on each level. I'll assume that the relevant line is dependant on the post and the respondent. What I think is worth taking away from this is that the level of argument raised in the response should be as high as possible.