Sure, but the answer to a lack of an informed public is not reverting away from democracy; it’s trying to inform the voters. Very many people vote against their best interests on a regular basis in a political sphere, and we shouldn’t revoke their right to vote as a result. Democracy, as a principle, should still prevail.
I don’t think it’s fair to infantilise people you’ve never met in the way that you are. What evidence do you have that the people who signed on to this letter didn’t read it? What evidence do you have that they’re either naïve or easily manipulated? I think they’re unfair assumptions. They may be true, but I have no idea if that’s the case.