jwz's thesis, that uninformed people shouldn't vote, is overwhelmingly correct. I consider myself to be well-informed, politically speaking. Yet I voted in only 7 of 17 races on my ballot. I am not, for example, equipped to make informed choices for my jurisdiction's school board.
All ballots should come with a "No vote" option. What would the difference be from just leaving it blank? Nothing, except that it would give uninformed people a box to tick so that they don't have to stray towards the more important ones.
With that said, his stated corollary (to vote against propositions by default) is unhelpful and perhaps harmful. Many ballot proposals are stupid. Some aren't. As a voter, if you don't have an informed opinion, the right move is to leave it blank. Don't vote. Leave the job to those who have done their homework.
Some argue that the idea is that, for x= 50 or 66 or whatever, you want "x% of all people to have heard about, understand, and agree with it" as opposed to "x% of people with an opinion agree with it". If you believe that (to be very explicit: I am not certain what I believe, so please do not start arguing with me personally about which is better; at best I oscillate), then the default should be "no". (Arguably, it might even make sense to have different defaults for different kinda of things, as we already do with different values of x; as an example, sometimes tax laws rwequire x=66 while other laws only require x=50.)
It's worse than that even. Having served as an election judge (and hence been obliged to assist those who needed it), many people needing help will ask "Which of these is the Republican option?" (where Republican = their party affiliation), even on issues that weren't particularly partisan, or national, or that even made sense.
The tact there being that party affiliation was more important than expressing their own choices, which isn't something that I understand in the slightest, especially as how centrist most candidates are.
It's pretty basic tribalism. "I am a Republican. Therefore, I will vote for the Republican option, unless I have an actual reason not to."
In front of that, there's probably, "My parents were Republican. My family is Republican. My friends are Republican." And so on.
This isn't actually wrong, per se. It's a basic affirmation of trust in one's close network. Some people go to church without bothering to believe in God; they go because they've always gone and their parents go and their friends are there and they discuss the football game or whatever. They're passionate about things because all of their friends are passionate about it.