I live in Denmark where we have a digital identity called "nenId". It's the safest form of citizen identification we've ever had and it would be immensely more safe for elections than our current system of sending out paper cards to be traded in for a vote.
On top of that the block chain could offer us a record that couldn't be manipulated.
Sure we don't have a lot of problems with voter fraud in our current system, but that doesn't mean it's not extremely vulnerable because it relies on honest counting.