Many of us consider ourselves rational creatures. We like to think that we evaluate tools and environments on their merits and come up with the best tool for the job.
Then the flame wars start:
Linux vs Microsoft
Emacs vs vi
Language zealots (I think most languages have zealots)
There are some serious cliches here. And in almost every case, the arguments devolve rapidly from rationality into "well... just because!".
When a decision is unfounded by merits, and is based solely on some irrational belief or preference, that's what I call a Diva Moment. "I use Ruby all the time because I just can't get anything done in a language as overbearing as Java!" Diva moment. "I can't possibly work on a mac; it's just too cute." Diva moment.
Most of us have our diva moments (or our diva topics). I, for example, refuse to use iChat because it just feels wrong. So I use Adium. Would using iChat kill me? Nah. Is iChat plus Messenger really any worse than Adium? Not really - both of 'em let me talk to people. It's just my diva moment.
It's normal to have diva moments, but we need to recognize them for what they are. And then we need to recognize the cost. That guy who refuses to use Java might miss out on a cool new job because it's a Java shop. Sorry, buddy. The anti-UNIX geek creates a persona, intended or not. That is the choice we make when we choose our irrational preferences. And that's okay. Just recognize that it is a choice, and the choice is yours, and the are yours consequences, too.