IntelliJ isn't the only program that does it, I've run into a few others.
But every time it's "undo, undo, undo...ok redo...fuck, why did that just delete a line? Oh, stupid keybinds. FINE, I GUESS I'LL RETYPE IT."
I don't mind ctrl-shift-z being redo and not ctrl-y, it's the binding something destructive to ctrl-y that irks me. Yeah, just completely fuck with someone who's never used your software before so they can't fix the mistake because they didn't know what your keybinds were, that's just brilliant.