That is called disagreement and shouldn't be downvoted. Moderation isn't to express agreement.

Expressing disagreement is expressly an acceptable basis for downvoting, and given the more general purpose of voting (expressing whether or not a contribution is valuable), while not all disagreement involves perception that the thing disagreed with isn't valuable, that something is inaccurate or wrong certainly can be a reason to conclude that is not a valuable contribution to a discussion.

People downvote incorrect information all the time.

While you may disagree with my opinion on what is the better type to use, I believe everything I said in my comment was factually correct.

size_t's raison d'etre is portability, you should be using it for things that are indexes/sizes into memory. FWIW, I don't have the karma to downvote.