Just my 2 cents on this.
If I understood the concern correctly, you are saying that because the full chatters list of a channel is no longer publicly available there can no longer be a maintained list of possible bots, determined by counting how many channels an account is in. You mentioned using this bot list to identify botnets/C&C bots
However, using this list, or any list for that matter, doesn’t actually solve this issue as you may have thought. Any possible idea of trying to proactively ban malicious accounts before they have a chance to do actual harm becomes irrelevant because of how trivial it is to make them undetectable.
This is because your method relies on these accounts just sitting in channels, doing nothing. The problem is that there is no reason for a truly malicious party to be constantly connected to a channel to do harm, it simply needs to join on demand. The bot accounts that are always in the viewer list are in the best case just someone messing around with twitch for fun, seeing how many channels they can join, and in the worst case some random script kiddie that doesn’t have any sort of sophisticated plan, just to get a kick out of some one off event.
In fact, the account doesn’t even have to join the channel to ever send a message in it, just be connected to the IRC server and specifying the channel it wishes to attempt to send a message in. This latter case probably wouldn’t be an as common solution as the former which is why I wanted to mention both.
Using a bot list for this use case just gives you a false sense of security since any truly malicious party that puts even the smallest amount of thought into trying to hide themselves will make any list completely irrelevant for proactive action.
Don’t get me wrong, I’m not denying that these bots aren’t a problem, I just don’t see how a public chatters list provides a meaningful solution for them.