I think that's the wrong way to approach /r/all (a subreddit that aggregates top posts from across Reddit). It's aim is to give people a look at top posts from across the site. If it gets dominated by any one subreddit - even if that were an innocuous subreddit full of of cute animals (like /r/aww) - it's an issue that would need to be fixed by changing the scoring algorithms. /r/all is not a prize for people to win, it's for readers to get a sense of major posts across the site.
On top of this, the Trump subreddit wasn't even legitimately getting most of it's posts to /r/all. They were actively trying to manipulate things in order to flood /r/all - making a sticky of new posts to get rapid upvotes, saying they would upvote any post on the subreddit, etc. The result was that the usefulness of /r/all went down, because a lot of it was just posts from one subreddit. The posts in the Trump subreddit also aren't innocuous. After the U.K. parliament attack, for instance, they made a post with the title "But hey, it wasn't all bad. In the end a Muslim was shot." that got ten thousand upvotes.
The_Donald's strategy was one of depth: focus on one subreddit aND it's content and work the algorithm to get to the front page.
The resist subreddits strategy is one of width: lots of subreddits where they focus on one or 2 posts in their subreddits network to get visibility on the front page.
The resist strategy is more annoying because there are too many different subreddits that they control to effectively filter them out
On top of this, the Trump subreddit wasn't even legitimately getting most of it's posts to /r/all. They were actively trying to manipulate things in order to flood /r/all - making a sticky of new posts to get rapid upvotes, saying they would upvote any post on the subreddit, etc. The result was that the usefulness of /r/all went down, because a lot of it was just posts from one subreddit. The posts in the Trump subreddit also aren't innocuous. After the U.K. parliament attack, for instance, they made a post with the title "But hey, it wasn't all bad. In the end a Muslim was shot." that got ten thousand upvotes.