I don't think it's marketing teams. There are at least a half dozen CoreOS employees/contributors commenting here, plus a couple of known allies. On the "other side" there's Bryan, me, and one person who seems to be an ex-employee. AFAIK
none of them are in marketing, or even in coordination with marketing. Certainly, I often get flak from my company's official mouthpieces for saying things that conflict with their preferred talking points. They
wish they could control what I say.
Mostly I think this is a matter of people naturally standing up for their friends and colleagues, which is a wonderful thing, vs. people who have specific concerns about The Right Way to do either technical or non-technical things. No coordination or collusion is necessary. You can see exactly the same thing happen for every company or project that's discussed here, or on Twitter, or wherever. Try criticizing a YC portfolio company some time. Not all of the people arguing with you will admit their affiliations, and of course the downvotes are all anonymous anyway. Just remember, the more skin someone has in the game, the more tempted they'll be to cross that vague line into astroturf. All the rest of us can do is admit our affiliations and biases, and hope that people will get their heads out of the ad hominem gutter enough to reach rational conclusions about the facts being presented.