Sims and aggregate websites are awesome tools and super helpful, but the average player seems to totally misuse them. It's really driven the hive mind effect to probably one of the highest levels ever - and warlocks are a great example of this. People see that Observers sim the highest dps - dissent matter if they're only a hair better, they're the best damnit! So now you see people doing pants on head retarded things like using observer on every single encounter.
People see Demo on raidbots and think it's an accurate picture of what the spec can do, and they call it trash. Now once you get out of the top 3ish % of raiders you see that the overwhelming majority of Warlocks play destro on every fight. It's so silly, not that Destro is a bad spec - obviously it's very good - but people are like brainwashed into thinking Aff is only viable on 1-3 fights and Demo is trash. It's really sad how people will probably jump on a Demo lock and tell them to respec because of a wipe at this point in the expansion. If you wipe it's not because you need cutting edge damage, it's cause your group as a collective is fucking up.
I'm in a lucky position where I'm playing in a guild with people who respect my skill as a player. I have nothing to prove so I can play whatever I want whenever. But like Jessikcka has said, in a lot of guilds when the boss doesn't die questions get asked. And that really sucks. Nothing is worse than being benched or asked to respec - especially when there are numerous things that probably need fixed that are way more important than spec choice. If you're in a world first guild that's totally different, and that does matter. But everyone else? No way.