> Ryan notices one of the single women that checked in and proceeds to watch her all night as she gets dangerously intoxicated.

This part is not enabled or disabled by a dating app. Ryan can do the same thing by hanging around bars and following their patrons around. I do think, though, that the problem is that some men seem to develop unhealthy obsessions with pictures of women they haven't yet met, and that stalkers will definitely spring from this app if it gains traction.