If we assume that voters are unable to deal with misinformation then we have already given up on democracy. The next logical step is to decide how to blunt the will of the misinformed voter.
Depends on what you mean by democracy. Suppose you get 100% voter participation through free and fair elections. Are you still sure that fails the definition of democracy? How hard is it to make that case? What if the voters choose an outcome you just don't happen to like? Is that all of a sudden undemocratic?
Consider holding a referendum that specified nobody who hadn't yet been born as of the referendum date would ever be allowed to vote.
It's a purposefully silly example (HN isn't for political debates!) but broadly, it's a democratically made self determination that reduces or precludes the ability to make democratic decisions in the future.