That's a burden we all must bear, for the sake of not degrading the site. At least we all bear it equally.

I managed to get answer from one of such downvoters: "I don't know, but it looks contradictory to general knowledge, so I downvoted you".

I hope, it will help.

If you have high IQ but lazy at explaining of basic things for regular Joe, regular Joe will downvote you, because he cannot follow you nor discuss with you.

At work, to check is my explanation is simple enough, I play a challenging game while thinking (I use sopwith, my IQ is about 140): if I'm able to think and play at same time, then my brain has some power to spare, so it is simple enough for people with IQ about 120. If not, then they will not be able to follow me. I use that technique for almost decade. Works well at work, when I have time to explain, e.g. in comments to tickets, emails, and so on.