However, removing the ability to down-vote won't really change anything in this regard, except that it will stop people from feeling attacked when they get a down-vote. What would change is that there would be no feedback about genuinely inappropriate comments, and I think that would be bad.

The only thing I can think of is to separate "down-vote" (meaning "of little value") from "inappropriate", label them clearly as such, and have the consequences of a "down-vote" less apparent and less severe. Then you can only trust that the behavior will sort itself as the "community" decides on the meaning of "inappropriate" and "of little value."

On the other hand, "int i = INT_MAX + 1" is factually wrong, and you could link to the standard to prove it. Similarly, "the Sun orbits the earth" is factually wrong (to the extent that it's meaningful, at least).

Yes, there are edge cases, and yes, people tend to think that what they believe in is "obviously" the only right thing to believe in; but that doesn't mean that there's no difference at all.