Agreed, I did not word it perfectly. But if you see the larger context the developer thinks that he has been picked on for not using Firefox, I believe they explicitly told him so. There could actually be other reasons, like you stated. If he was lacking in other areas they really should tell him that. My point here is that most of us end up judging each other very harshly. (just like you judged that I was pretty clueless on the larger context, because I did not articulate something imperfectly). Collectively speaking we developers are our own worst enemies.
Also just a comment on your original comment, where you essentially stated that inter-personal skills are also important. In toxic work environments often individual contributors are dumped with so much of work, that if they even ever attempted to help/interact with someone else they would fall behind on their own work. And then they are held task for not doing their work. I have seen this multiple times pan out. Remember you are dealing with unreasonable people, and they will get you in the end no matter how good you are, if they do not like you for some reason ( for example you are a different ethnicity, and you don't speak their language, which may not be English)
You emphasized only!