I've experienced the need to change the "conventions" with people resisting it and the "how much to optimize is too much" dilemma, but I find those kind of discussions actually productive. People can learn with those.
Lately, the religions that actually annoy me are almost everything happening to javascript ("what framework?", "what version?", "what stack?", "what task runner?", etc, etc). I'm yet to find one argument in that realm that wasn't completely asinine.