Why do players leave ladders?

In recent days, a lot of players have the status of "Leaving". What happened? Is it just preparing for a new flood of games on July 1, or is the system removing them from the ladders?

I left a bunch of ladders b/c of the past/present/future tournament floods.

I left all mine because there are a bit too many games going on at once. I only want one at a time in each ladder, but I'm getting up to three at a time.

It would be nice if this were configurable, but that may be a bit complicated.

I left all my ladders because my wife had a second kid.

Without checking with you first?!

I'm scared of heights, and some of them are very tall.