In my experience when Reddit banned the more toxic subreddits many of the other subreddits I actually did frequent became better. I think the people who would be in those subreddits are already there and when there are bans in subreddits some of the people leave and the community is better for it.
The thing is that those people are also on other subreddits, people generally don't frequent just one. So those people always bring in Reddit to comment on the Donald is also leasing to more engagement on other subreddits. It's possible that the Donald would organize more and be more of an issue in other subreddits but that wasn't how it worked in the past.
