Board Thread:FAQs/@comment-37572562-20181120175503/@comment-31953669-20181121141531

Of course, semblance stealing would not be a functional semblance.

It doesn't work on Grimm, so they'd be a useless character except against other humans and faunus, and then would probably only work on the ones with an unlocked Semblance which some perfectly competent fighters (like Roman) never unlock.