Some of the abuse clearly rises to criminal levels, but not all of it does. Merely punting the issue over to law enforcement potentially improves the situation[1], but it doesn't solve it - there's plenty of non-criminal abuse that still reaches a level that discourages people from putting up with this shit.

[1] But not necessarily - involving police isn't an automatic mechanism for making things better, and there are plenty of cases where a victim going to the police has ended up making things worse in the long run