First of all I've never played an online match in my life, mainly because online play sucks, mainly due to the lack of support for people new to online games you either get booted by people hating on newbies or abused, so for me there's no point in me ever playing an online game ever unless it's with my friends.
But:
Why are people so annoyed at campers?
Logically they're the ones doing the sensible stuff in war. Waiting, out of line of sight, striking when the enemy is close and vulnerable.
It's really those who go around all guns blazing which are the stupid ones.