To be fair, they came in with some requirements that I don't think anyone else had at the time, and even today aren't in any mainstream ones afaik. I think the

To be fair, they came in with some requirements that I don't think anyone else had at the time, and even today aren't in any mainstream ones afaik. I think the biggest difference was around providing security and stability barriers between front-end components on the same page, with the intent of allowing you to compose a page that contains your own components and those of other third party applications you've installed with guarantees about how they can (and can't) interact. Not sure they couldn't have tacked that onto another framework, but it comes with enough trade-offs and compromises that I'm not sure anyone else would have wanted to upstream it, so they would have been forking something anyway. Aura wasn't much fun to work with, was never really feature complete, and not advocating for it... but it actually kind of made sense if you thought about front end with the context of how salesforce did security and multitenancy in mind.