Does anyone really think that Mozilla cares about this "advice"? They're overrun with "corporate haters", and entirely too used to their paychecks coming from handout/entitlements (where does the Mozilla Foundation get its money, after all).
They've just shot FireFox in the head, and their hubris won't let them see that. When you antagonize end users, developers who are developing for your platform, and decision-makers, bad things will follow. Of course, over the next few months as their market share will drop to 20%, then 10%, then single digits, they'll blame everybody except themselves. That's the classic pattern, after all... don't listen to what your customers need, TELL them what they need. If people aren't using FireFox, the problem lies with the people, not FireFox.
These are people who not only think they are right, they think they are righteous. Funny thing about being the Chosen Ones... some people can't tell the difference between the hand of God on their shoulder and the dick of the devil up their ass.