Unfortunately, they all VPN and hop around different IP addresses all the time. They avoid any email bans too, just make a new one and keep going. I am very frustrated with the spammers as well, I wish there was a simple solution, but they'd figure that out too. I am hoping to find something effective to do soon, but we'll see if actually helps.
I've considered it, but it's difficult to separate fake from real.
For example, if I just made it a requirement that you create a guild site to post on the support forums, the spammers would figure that out and create a site. It might stop some of them for some time, but not for long.
Let's say I add to the requirement that you need to have at least one member other than yourself. Spammers would figure that out and create another account and add themselves. A regular user wouldn't necessarily figure that out because that's not what they're thinking about, they aren't thinking about gaming the anti spammer system, they're just trying to use the product. A user may come in and want to just spin up and tinker with a site to decide if they want to use one at all or if they want to start a guild. They might think of a question and pop onto the support forums and see the error message that they need to have at least one member on their site, then they get frustrated and leave.
It's those types of issues that I want to avoid at all cost. Near zero friction for regular real users.