What constitutes "good" moderation is a whole other topic, and one that I don't have enough expertise to give more than random personal opinions on. (And my random personal opinions would probably piss off a lot of people.) My point here is that just because good moderation is hard (true) doesn't mean we can or should avoid it. Calls for "no moderation" are, almost invariably, born of a desire to not be yourself held accountable for your actions, and even if well-meaning lead to community death.
I didn't say that we should ban/shun anyone that does not uphold a particular standard as a first-step. Sometimes banning people really is the best solution, but it's always better if something else can be done instead. (Education, mediation, timeout, whatever.) If those don't work, though, then removing a toxic element is better than trying to mediate between toxicity and everyone else.
The individuals banned from the PHP Internals list in this case had been sources of trouble for literally years. Their removal was long overdue.