I've heard the claim a lot that Blockchains are great for elections. And in theory, I'm convinced that if you get all the external moving pieces right, then yes. It IS a viable and trustworthy alternative to the real thing. The only problem is all those external factors of which there are many. This blog post by Terence does a damn good takedown of all of it and is fully worth a read.
I went to an event a few weeks ago where some leading BlockChain organisations were showing off the power of Distributed Ledgers and how they will transform society. Not one of them mentioned users.
There was talk of investors, stakeholders, corporations, smart-contract-backed entities. But no users.
The underlying greater issue of Blockchains based apps being built with little to no consideration of actual usability is the key takeaway here. I think Blockchain could succeed, but just like distributed social networks there's a ton of problems to solve/make easy before you even get to the main idea at hand.
While we are on the topic of voting systems though, there's this equally great takedown of e-voting systems by the always charming Tom