I can see lots of reaosns people might oppose the idea but I am not sure why it's not a widely discussed option?
(asking honestly and openly - please don't shout!)
If someone walks upto me in the voting booth and says "vote for X or I will kill you" that's a crime. If they do it in the pub it's probably a crime. If they do it online the police don't have enough manpower to deal with the situation.
We should change that.
Every time some fuckwit tweets "you and your kids are going to get raped to death and I know where you live" because some woman dares suggest some political chnage I would like to see jail time.
And if we do that then I can understand your argument, but I would then say it is not valid - in a society that protects free speech.
Much more likely is that I'll vote ignorantly because I lack information that someone withheld because they're intimidated by the authorities.
All of those notions are pre-internet ways of proving identity. In a world where we're all rarely more than an arm's length from a globally connected computer, they're on the way out.
I am very aware of "designing a security system they themselves cannot break" and the difficulties of key management etc.
Would be interested in knowing more from smarter people
(probably need to build a poc - one day :-( )
I think there are cases for anonymous/pseudonymous speech, but I think that's going to have to shift away from disposable identities. Newspapers, for example, have been providing selective anonymity for hundreds of years, so I think there's a model to follow: trusted people/organizations who validate the quality of a non-public identity.
So a place like HN, for example, could promise that each pseudonymous account is connected to a unique human via some sort of government ID with challenge/response capability. Or you could end up with third-party ID providers that provide a similar service that goes beyond mere identity, like the Twitter Verified program scaled up.
Disposable identities have always been a struggle. E.g., look at Reddit's very popular Am I the Asshole, where people widely believe a lot of the content is creative writing exercises. But keeping up a fake identity over the long term was a lot of work. Not anymore, though!