That only works if they have a static IP address...
It might stop them for a day or two, but it also runs the risk of cutting off any other members who are with the same carier.
They need to make SRP have a persistent cookie, maybe a java one that can be activated by a moderator for these spammers.
That way once a spammer is identified, the cookie can basically burn their identity into their computer, don't allow them to sign out, and make it automatically redirect them elsewhere when they try to open the site.
This isn't illegal, or immoral, it isn't even difficult. They come in as one id, spam, get banned, and the next time they try to access the site instead of seeing SRP come up on their screen, they are automatically redirected to
Barney's web site...
and because the SRP cookie is made to be persistent, and to not allow them to log out they would have to erase the cookie before they can access the site again under a different ID. This is easy with regular cookies, but still takes time, with Java cookies, it's darn near impossible.
The plain and simple truth is these spammers don't have time to mess around with sites that fight back. They come in post until banned and move on to their next ID. Many of these spammers are probably the same individual with several member names.
Why should the Moderators have to bann the same guy 10 times a week.