Just think about how many times the internet could be a better place if some dickhead mod didn't say "Well TECHNICALLY he didn't do anything WRONG." like social spaces are the text of a Magic: the Gathering card.
No. Throw the guy out.
simple. easy. and yet we still deliberate
These are great and having a "mod decisions are final" thing up front is a good signal to assholes that they can't pull one of their favorite entrenchment tactics: socially dividing the moderators from the broader community and convincing them that everyone else will turn on them for being megalomaniacs if they ban one disruptive fuckhead.
A constant of community management is that if you let a rules lawyer gain a foothold they WILL suck up as much air as they possibly can. Assholes are very, very good at making their targets feel like anything short of smoking gun evidence of deliberate wrongdoing will result in divided opinion and massive backlash. They can maintain this illusion with incredible success even in situations where their bullshit is basically the sole source of drama in the community.
I'm not sure why this happens, but my best guess is that most people don't really enjoy being in conflict with their social group and deliberately, maliciously starting shit just bewilders us. The idea that someone would actively try to be disliked by and hurt people who are inclined to be neutral/friendly doesn't have a good explanation, it's stressful and upsetting, and it puts people on the defensive. In the abusive relationships I've been in--most of them friendships--the opening volley to start controlling behavior almost always involved wildly disproportionate anger or hurt at something that healthy adults could have resolved in five seconds with, "Oh, shit, sorry." "Hey, no problem." A rando doing this may get the door shut in their face, but when it's a friend or someone you're meant to cooperate with it prompts a repair response--they wouldn't be reacting like that if something wasn't horribly wrong, right?
Now introduce the fact that moderators and community managers of most modern social media sites or video games or other public communities are employees of major companies who are handling a customer. This is actually a major reason I think social media has sucked so badly for humanity--a dipshit dealing with an employee doesn't have to make them feel isolated from the community and unlikely to be supported in their moderation decisions, because their employer has already taken care of that. They know whoever they're dealing with has very little autonomy, has to be polite to them, and if they complain high enough up the chain about being banned for anything short of confessing to murder they can probably get them reprimanded or even fired.
You don't have to ban most people in a normal community. You don't even have to warn most people in a normal community. The time and effort required to keep giving, say, a toxic player repeated chances to be a productive member of a video game community can be far beyond what's required for everyone else combined. The Zendesk back and forth with some of these fuckheads is nothing but months and months of them accusing moderation staff of personally targeting them and ruining their life for temporarily suspending them while the mods patiently try to explain to them why their behavior is unacceptable. The internal discussions all boil down to, "Well, we can't ban them, so now what?" because everyone knows that unless cops are involved the burden of proof will be on the moderators to show that they did everything in their power to keep a user onboarded.
Also, the number of true fuckheads who will just immediately go to Reddit and straight up lie about why they were banned is pretty staggering. One of many actual examples: "I don't know what I did! I think they banned me for naming my character after a dog. :(" and the community rage only ended with the reveal that they had actually just been calling people racist slurs. But usually the mods don't get a chance to clarify.
Everyone is so used to this that it's actually visible in some of the kneejerk fear about Cohost and other small platforms. A lot of digital ink has been spilled arguing that we've seen vague rules leveraged to punish marginalized people before, which is true--but the whole argument presupposes that there is or will be an authority above the people who wrote them who can veto or mandate their enforcement, and that the people responsible for interpreting them are not supposed to bring their own values or opinions into moderation decisions. Even if that opinion is just, "Wow, what an asshole."