/u/spez addressed it a bit in his AMA. [1]

It was a problem. A smaller problem, but still a problem. As I mentioned in my post, r/all has gone through waves of being overwhelmed by a specific community many, many times over the years. Sometimes it's healthy, sometimes it's funny, most of the time it's annoying, particularly during election years.

[1]: https://www.reddit.com/r/announcements/comments/4oedco/lets_...