I tested a bit, it's obvious that for you the same computer is the same IP, although for the registration attempt I used another computer, not this one on which I'm writing this.

This way you block entire networks, both home and office, various open networks where many people use the same IP, and at the same time you don't prevent access to those with dynamic addresses (e.g. most siol users).
I think repressive policy on forums doesn't pay off, on the contrary you embitter the life of potential new users, who about such a forum that requires an email request for registration, well they think what they think. In the future will a written application and copy of ID be needed?
It would make sense to delete messages that annoy the majority, not to carry out blocks that experienced users can of course bypass. If I wanted to spam, I can make a bunch of new users, with minimal work for each use another proxy, or access via anonymization network (tor). Even simpler is to use neighbor's unsecured wifi for registration, there are still plenty.
Senseless debates are simply reduced as larger forums do it - that insolent or offensive message is deleted immediately or asap, of course the forum must have a team of moderators who regularly read the forum, this seems like one-man-band?