Net neutrality is good for an open internet which is not controlled by ISPs.

Net neutrality means that ISPs should not shape traffic as they see fit. Not even when it's "illegal traffic".

So net neutrality also means that governments can't force ISPs to shut down your internet because you're suspected of a crime by potentially fining the ISPs for any illegal activity that you might be doing. So ISPs would rather just shut down your internet access before it even gets to this point.

So think of net neutrality like asserting that the internet should be more like public infrastructure. If the net is not neutral, it's no longer public infrastructure.

There was a lawsuit where some government wanted to fine ISPs for piracy of their users. The ISPs tried to argue that they can't be fined since Twitter also wasn't fined for terrorists using their platform. And ISPs have even less control what goes through their networks. But can't find it at the moment.

Here are some sources which I haven't verified myself but the headlines look like they go more into depth of what I am trying to say: