The biased comments here are too childish to smell professionalism and probably hurt the brands more than help. Florian posts are extremely professional and often fool many readers and even other professional bloggers. Compare that to the average HN/reddit trolls. [1] Huge clear difference, I doubt any of them are professionals.
But your argument cuts both ways. If a poster doesn't seem professional, then they do seem "real" and showing you have real fans may seem useful to companies.
Apple in particular probably doesn't need that but a company like, say, Microsoft might feel they'd benefit having trollish fan-boys making their case (making them, indeed seem more Apple-like), since they also wouldn't have to answer for the arguments of these "obviously unprofessional" fans...
[1] http://news.ycombinator.com/threads?id=taligent