There are several identity mechanisms that have been proposed claiming to be able to prove an account is run by a single human being, to identify that single human such that they cannot have multiple accounts, and as far as 1a1v on Hive, I am not willing to limit such democratic voting by any other metric than that.

I was addressing exactly this issue years ago with one of the witnesses, and was told that such identifying function was either not doable or could be tricked, as well. I am not sure any more what exactly was said but the overall message was "no".