The problem is that it has become very popular to ban people from a sub based on what other subs they post to. It was turning Reddit into a two-party universe.

The better fix would be to make the support for multiple accounts in the reddit app not so incredibly-shitty, where you're basically logging out and logging back in. Instead, just tell it "posts to this sub use this account, posts to that sub use that account", etc.

That two-party universe thing comes from the issue of having to moderate, and moderation is ideological by nature.