Yeah I was wondering the same thing, looking at this it seems they have been pretty active at it, even removing a Tetris android wallpaper application.

Probably because Tetr.io is non-commercial ?

* https://www.reddit.com/r/Tetris/comments/ka43wx/tetra_online...

* https://www.reddit.com/r/androiddev/comments/1vzwe8/got_a_dm...

* https://harddrop.com/forums/index.php?showtopic=8135