I think the main problem is that there's no real solution that doesn't open the door to several other problems. You institute email verification, these trolls will just start making multiple email addresses. You institute a reporting system, the could lead to embittered users trying to weaponize that against people they don't like. Ultimately, the best system to do things is to have a committed and vigilant community that proactively combats troll that want the collapse of our good-natured exchange of ideas. It's up to the community to work together to purge the trolls.