[eyezick]

Depends on the specific implementation. Just because you do it on a blockchain doesn't mean you can't require people to show up to a polling center and sign transactions in person.

With Ethereum, one way to do it is to make the voting weight non-transferable, meaning to give someone else your vote you'd need to give your private key.

It would be of course crazy to do that; like giving someone your bank card and PIN number to give them cash.