Quote Originally Posted by VeryVoodoo View Post
Well it actually lists the ability dmg not stacking up as one of the bugfixes they did on the May patch in jp wiki.
That's not actually what it says. It says an ability damage effect (stacking) was added. It does NOT say the effect was changed from non-stacking to stacking.

If you look at the page as it read in 4/2017, it looks like this. Notice that no ability damage effect existed at all at that time.