I don't think that's entirely fair. Sometimes who someone is, is a decisive factor in what arguments they present. It can give them a valuable jolt of insight to point out that they present those arguments because they are missing part of the view. Of course you should also explain why the arguments in themselves are wrong, but the main argument may be "you've never experienced X; those that have tend to argue Y, because of Z"
It's very easy to make those arguments just by saying "From my experience doing X, you're wrong because..." without speculating about what the other person hasn't done.
on the contrary, I find communicating in this way a rather reliable method of talking in short hand. I was happy to be wrong, since phk illuminated another reason why some people may advocate breaking compatibility, and it is easy to get to his core arguments once his credentials were established.
