inefficiency here can actually be useful, it's similar to password stretching. If you know someone had to burn $10 of electricity to make an authentication, it hurts more to get banned.

> inefficiency here can actually be useful

Except for the tons of CO2 that get pumped into the atmosphere in the process, or the blackouts its causes, or the fact that there are tons of more useful applications for that energy, like heating homes, running air conditioning, charging electric vehicles ...

Fine when MasterCard and Visa do it (poorly) though!

> If you know someone had to burn $10 of electricity to make an authentication, it hurts more to get banned.

Metafilter charges $5 to get an account. If you can't afford the $5, you can email the mods to join for free.

SomethingAwful charges $10 (and offers a platinum account, and a paid add-on to view old threads).

Both of these payments are done through PayPal, and both exist as a way to filter spammers and trolls.

I thought the whole point of decentralisation was that you couldn't be banned though.