I total believe that blocking IP's is a stupid method to stop spam. But if you also capture the hard drive serial number and Mac Address with the IP address. Then you have a perfect solution. I did a lot of work concerning IP blocking many years ago and know all the damn problems. I was totally amused at the wall.fm problem and believe me IP checking on its own has problems that can not totally be eradicate. The tends to upset the site users, that is the big issue with site owners.
It does not matter how problems have been solved with IP Spam blocking, they will still have a problem. I believe I spoke some many years ago to guys on Wall.fm about all the problems involved in such software, what happened a total mess on wall.fm. Lol
There was even a data base being check when the plugin programer did not have the permission to do so.
It does not matter if its free, that is not the point
One does not need it and if you do have a high usage site then dealing with the complaints of blocked users builds up becoming an admin time wasting problem. The other point being putting a IP that is also being used by spammers, lets the spammers back in. lol
Totally crazy.