I've come to find that I get really irked when people express that everything should be open source.
The crazy part about this is that I actually agree with those people! At least, that literal sentence.
But it irks me because of the underlying attitude that a lot of diehard FOSS advocates have. The implication being that open source is ALL you need to make the world better. Which is complete nonsense.
Open source is important, but it's just one piece of the puzzle. Modern software has so many problems and you can't focus on just one problem.