Now, perhaps many of us blogging types have too much copy writing experience to not find something wrong with just about everything we read (eg, everything on this page), but the points remains that good copy is usable copy (and usable copy matters). Your writing should provide context to the user within the scope of their experience, and leverage their understanding of the issue being discussed. Too often we fail to keep the message personable and suffer from Haller's oft described 'disease of familiarity' and go off the handle and rail on how much Netscape 4.x sucks ass.
In the case that Kaufman points to, ESPN tells you sort of abruptly that your browser sucks (if they sniff a particular browser). Well, they are probably right, but stepping on toes doesn't help the situation and likely achieves absolutely nothing. My advice? Don't make a point out of something if it's going to be pointless, otherwise spend a minute thinking about being helpful, and how to best execute that helpfulness.