This would work if governments were empowered on a granular level, but they aren't. If you've decided (Republican|Democrat)s are evil then you'll always vote for the same party, and there is no accountability.
> Which describes some voters but certainly not all. You'll notice power changes quite often in the US, clearly some voters are changing their minds.
But not on individual issues like this, unless they are extremely important to many voters, and highly party-aligned (e.g. abortion). You vote for one party or the other, each of which having 1000s of positions like this.
> In any case, what's the endpoint of this argument? Democracy isn't worth it because voters can get polarized?
The endpoint is not thinking that democracy as it stands can reign a lot of things in, unless they become the issue for an election. Not every issue can become the battleground of an election, but there are alternatives to fighting.
Which describes some voters but certainly not all. You'll notice power changes quite often in the US, clearly some voters are changing their minds.
In any case, what's the endpoint of this argument? Democracy isn't worth it because voters can get polarized?