As a non native speaker, the only times I have ever seen people using the word outside of its dictionary definitions when I was reading a bit of MAGA/Q sites out of boredom last year. I took it to just mean something based on US style christian/conservative values.

But usage seems to be broader according to what you wrote. I reckon the most common usage will be, that something is based, when it is unpopular or contentious, but you happen to agree with it.

The usage on MAGA/Q sites is entirely a consequence of the huge cultural influence that boards like /pol/ have exerted on the online far-right. After all, the entire Qanon movement basically sprung out of a /pol/ fairytale.

Thanks for explaining "based" - I didn't know what it was. But I don't understand how your example is actually an example of that. "Rowling is better than Hemingway" is a matter of opinion, so it can't be "unpopular but correct".

When I say 'correct', I mean correct in the eyes of the person using the word 'based'. It's worth bearing in mind here that imageboards for the most part have a wilful cultural neglect of the difference between 'my opinion' and 'objective truth' :-)

> unpopular or contentious but nonetheless correct.

I agree with that, but regard it as an evolution from my other answer meaning "established." The reference to contentious or unpopular comes because a based person has earned the ability to present unpopular ideas without repercussion.

I think you're right that the term originates in hip-hop culture but when it was borrowed by imageboard culture it evolved into a descriptor of ideas and not of people - for the simple reason that imageboards are mostly anonymous.

Now when I see the term used online it's mostly in the imageboard sense of some idea or concept being 'correct' or 'agreeable' rather than the person who originates it. I think the term is undergoing a certain amount of semantic broadening too - more and more often I see it simply as a synonym for 'cool' rather than in the narrower meaning of 'this is controversial but I agree with it'.