The number of allowed difficulty ownership changes over a certain period should be limited

[Nivalyx]

Related to this recent incident where someone maliciously tried to "mass ping" a bunch of mappers/users by changing the ownership of a difficulty over and over.

I feel like this is definitely an oversight, as this feature should definitely not be possible to be abused this way.

There should *really* be a limit as to how much regular users can change difficulty ownerships on a set they own, perhaps somewhere around 3x changes per diff per day.

[nanaya]

Yeah I don't know when it's also a fast track to getting yourself banned.