E-voting seems to need exactly what a blockchain offers — so why does Do You Need a Blockchain? (Wüst & Gervais, 2017) stop short of endorsing it?

Because e-voting's requirements pull against each other (anonymous votes vs public verifiability), and no proposed system has yet been shown to be simultaneously secure, verifiable, and private.

E-voting genuinely matches the blockchain profile: many mutually distrusting parties, and a hard need for public verifiability (otherwise the voting provider — or whoever compromises it — could silently change votes). But it also demands privacy: votes must be anonymous to prevent coercion and vote-buying. These two requirements are in direct tension, and satisfying both at once is the crux of the difficulty. So while blockchain technology can help with some properties, the paper's honest verdict is that — as of writing — no scheme had been demonstrated to be secure, verifiable, and private together; many open challenges remain.

Go deeper:

• Electronic voting (Wikipedia) — the competing requirements (verifiability, secret ballot, coercion-resistance) that make secure e-voting hard.