As I understand it, both are interrelated. I've seen the very same thing in paper magazines. Let's say we look at a magazine about... ties. There is a symbiotic relation between the brands (even if there are more than one) and the writers. Writers help the brands to sell fabric and brands help the writers to sell paper.

It's not very likely that someone writing in such a magazine writes that ties are useless and outdated. Maybe they could say that foulards are disgusting or that people that refuse to wear a tie are unelegant.

That doesn't mean lack of honesty, just self-selection. If some writer dislikes ties, it's more likely that he ends up working for another kind of magazine.

However, there is a point when this gets a little too far: writing that ties cure cancer, insinuating that anti-ties are ugly unkind persons that can't stand others' elegancy...

Is such person really so fanatized that he really believes that crap or is he just exagerating to push the business? It's anybody's guess. But IMHO this question has been answered for Gruber years ago.

Oh, and just one last thing: I assume that being a friendly blogger gets him a lot of perks, from free hardware for testing, some information earlier than anyone else, conferences tickets, that kind of thing.