Moderation Enforced

I just find it hard to believe that every person you ban has the patience to change devices, IP addresses and login info every time he gets banned just to post in a forum where he's obviously not welcomed.

#1) You can't determine the MAC address of a device connecting to you without actually running code on the machine doing the connecting. You can google the topic if you're interested, it's a very clear 'no'.
#2) IP Addresses are not social security numbers. They are not static. They do not identify people. They can change in a blink and on many ISPs and via many devices the IP can be one of thousands with no rhyme or reason or pattern. Cell phones in particular. Then you have to factor in proxies, which can let you appear to be anywhere in the world.
#3) Some banned people actually get the concept. The psychotic and idiotic do not. We have a long and nasty history of users who spend months on end just trying to prove that for every way we can remove them they can find three more to come back. Some to the extent of having created entire sleeper accounts just waiting to cycle them in. It's beyond ridiculous.

I personally find this to be stupid and a bit overkill. I also think you're being a tad overzealous on trying to keep him absolutely off the website.

Banned people have complete access to the site, just as unregistered people do. The only purpose in him recreating over and over is so he can post, and largely to post things that flaunt the reason he was banned in the first place and get himself some attention. His claims of wanting to be here for any reason beyond attention are proven complete BS by the manner in which he uses the posting privileges he keeps violating his ban to obtain. If all he wanted was to read us, he can do that just fine without an account, or even on any of the banned accounts.

He isn't posting anymore, really.

Because clearly he's an honest, trustworthy person who can be taken at the value of his word.