I moderate a couple of subreddits and agree moderation is a disaster. For popular subs, moderators are basically swamped in a never-ending avalanche of shit. Even if you want to be a good mod, doing so for the long haul is an insane time commitment.
The fact that being banned from one sub doesn't usually get you banned from another sub is totally understandable, but combined with how easy it is to make a new account, in practice it's just never-ending whack-a-mole with shithead posters.