Probably a mix of both. The "first offense perma-ban no appeal" button has got to be pretty appealing when you're dealing with a lot of spam, or someone hurt your feelings, or whatever. It got so bad I had to start using VPNs to make new accounts on the regular, and then eventually I just stopped commenting and started lurking. On some subs it was a game of "whoever gets reported first gets a permaban" so if I got into any arguments whatsoever, I was gone.
In some cases I could see it was incompetence (or, charitably, lack of attention). For example:
Person: says something racist
Me: quote their racist statement, then refute it
Person: reports my post for containing the racist statement that I quoted from them