It wasn't meant to be rhetorical nor calling proggit out by name. The very same thing happens within development teams when people "flip the bozo bit" on team mates for the most trivial errors and are biased against anything they say or do forever afterwards.
It can be a very serious problem when this happens within a team, IMO.
I'll answer the, perhaps rhetorical question, by defining a new law: "Any online community that doesn't actively encourage its users to be nice, and civil, to each other is bound to become a cesspool.".