As I mentioned in my other comment, I think the biggest problem with the phrase "proof of brain" is that participating does not actually require a brain. There are a ton of automated votes that are part of the steem ecosystem, so nobody has to prove they have a brain in order for them to participate. So if the idea is to have a proof of brain, the bar is currently way too low ;) Everything that's being done on the platform, can indeed be done without a brain.

It's a nice-sounding buzz word that has something to do with the typical blockchain terminology, but I think you guys should look for a better and more descriptive term, because this one is obviously inaccurate.