Just like XTools shows the data and statistics for the last 50,000 revisions of a page, en:WP:ANI as an example, it should show the data and statistics for the last 1,000,000 edits of a user instead of stopping completely and rejecting the request, eg BD2412's edit counts. The feature available for Page Info can also be implemented for User edit counts.
Topic on Talk:XTools/Flow
This is phab:T182182. It's been a while since I've done any tests, but in the past it was just too slow, even with the date range constraints. Things are probably more realistic now that we require OAuth. I'll revisit this when I have the time.