A subreddit with a fraction of the userbase and activity than other subs would constantly have multiple posts on the frontpage at any given time, and noone cared to look into it or do something against it. I wouldn't be surprised if that sub beat out some default subs during that time, which is just straight up ridiculous.
This shouldn't have happened, true, but the reason for that is not as much /u/spez screwing up than it is all of reddit screwing up.
You are talking about r/all, which almost no one browses according to the Reddit admins themselves. And as of a few months ago, at most 3-4 posts from any one subreddit are on each page of r/all.
Why exactly should they be banned? I can't help but suspect that the real reason is that you want to silence their politics.
To remove politics from the argument, I don't watch basketball. So if /r/nba decided they wanted to have all their posts on the front page and told their readers to up vote everything they see no matter what, I'd have the same reaction. It's not what the system was designed for. I want to see a healthy mix of what reddit users actually think are the most interesting posts of the day. One subreddit, especially one that's not even that popular, taking over /r/all is not what I want to see. Doesn't matter which subreddit. I want to see a good mix.
Another suspect thing is that time when the Reddit algorthm broke and the first 50 pages of r/all were turned into /r/the_donald post. Apparently what happened is that the sorting broke and they were ordering posts by activity, revealing that /r/the_donald posts were being upvoted at a rate that dwarfed other subreddits.
Disregard the title as it's not a "botnet." It's a user script that adds functionality to RES: automatically upvote everything in The_Donald, automatically downvote everything in other subreddits, and allows importing lists of specific users to up/downvote.
Reddit is gamed all over the place, in all subs. Between that, and fake amazon reviews, it's really feeling like this is a problem we need to start spending some time to try and push against.
No idea what we can do.. probably nothing..
Edit: to people downvoting, please elaborate.
This coming from a person who filters out /r/the_donald so I don't have to see it.
EDIT: Apparently reddit has changed the /r/all algorithm so this is no longer true. Thanks everyone for informing me!
Which basically looks like a political move and it is kind of sketchy in that regard, but for users like you it's probably beneficial.