I wouldn't be against certain restrictions like one account can only be created per ip,
As a Tor user, I would strongly object to that. It is likely that
many accounts have been created from whatever exit IP I happened to use when I created mine. I paid the requisite fee to absolve myself of that IPs evil. But had there been any restriction on accounts created per IP, then I would not be here at all.
Whitelising Tor for multiple accounts created per IP would not be a solution. Tor is not the only anonymity solution; and moreover, a whitelist of Tor exits would simply mean that all users who wanted to create many accounts would use Tor for that. Its likely that many of them already do, anyway.
People can first find a clearnet connection to sign up with first then use tor. I wouldn't be against users signing up via tor paying a (bigger) fee, and have in the past suggested that all connections are blacklisted once used to sign up via, but a user could then bypass that by paying a fee or buying a member rank etc to whitelist it for themselves. The point is to make it so creating multiple to hundreds of accounts just isn't financially worth it but people should be able to have one or two or as many as they can afford or pay for. I guess with the merit system the number of accounts you can have now for signature campaigns requires more work and will slow farmers down greatly but I think people will still find ways around it by trading or buying merits etc.