>In principle, downvotes are meant for messages that are irrelevant, off topic, insulting, belligerent (can you believe my phone turned that into beliebers?) etc.

In principle this is what it's used for, however it's mostly used to vote down comments people disagree or agree with.

For example if I say something like global warming is an incorrect theory on a related topic I'd get voted down simply because most people disagree. Technically that statement did no fit the formal criteria to get voted down but people use it incorrectly.