Why does Discord allow a server for a botnet owner?

There's servers where they just hang out, but which themselves are legitimate. Cybersecurity related ones etc. You can ban them and they'll just switch to another account within a minute. Occasionally discord or a server owner does, but everyone knows its pointless. There's probably other servers that are mostly used by cybercriminals, maybe command-and-control backups, and security researchers may stumble upon these when taking some malware apart, join them, and end up getting in contact with the owner.

In general I don't think law enforcement wants discord to take these down or ban them. These guys would have no problem to just make some IRC servers or whatever to hang out on instead, which would be much harder to surveil for law enforcement - compared to discord just forwarding them everything said by those accounts and on those servers.

Why wouldn't they? There are Discord servers about anything you can imagine and also what you can't or don't want to image. As long as they don't start disrupting their infra Discord couldn't care less.

Also, how would you even go about classifying them as botnet operators?

Discord has a lot of terrible servers. This is one of the reasons they were not trusted when they came out and wanted to do identity verification. They already have a lot of information yet fail to do meaningful enforcement at scale.

Ever tried to ban a botnet owner from a service they want to use?

It’s basically impossible. They have money, IPs, identities, anything you could possibly want to evade.

I imagine because banning these things is both whack-a-mole and like finding a needle in a hay stack.

botnet owners don't typically come forwards and say they are trying to run a botnet, so there may be some difficulty in detecting them there.

botnet owners dying typically come forwards and say they are trying to run a botnet, so there may be some difficulty there.