User blog comment:Rappy 4187/Technical Update: June 29, 2016/@comment-244709-20160630200444/@comment-1824272-20160630220216

I think people have been over-zealous about how much the Top Contributor list will actually change in terms of spam contributions. It's no different from having your name show up repeatedly in Special:WikiActivity or just increasing your edit count in the first place, which has happened tons of times elsewhere without Top Contributors. I doubt it would change that much.

That being said, you bring up an excellent point about the software itself - rollbacks should deduct an edit from the edit count of the user who made the rollbacked edit.