Not only that, but many of the common advertising bots are actually a vast pool of compromised accounts rather than dedicated bots. Which means by banning them you’re also banning legitimate users, which includes normal users, affiliates, occasionally partners, and even at one point a staff member was compromised.
Because the number of users is quite vast (for example, the ‘bigfollows’ bots regularly use between 7,000 and 16,000 unique accounts per day), even if you encounter one of them the chance of that same one being the account that goes to the other channels you mod for is unlikely, chances are it will be one of the many other thousands of bots so pre-banning in this situation will have little or no impact other than using up your rate limit for no reason, while potentially harming the channels if they ban legitimate users.