I've rarely seen a technology so eagerly embraced by both bleeding edge tech enthusiasts and also enterprise behemoths (granted, tech behemoths, but still)

Having API documentation that is guaranteed not to go out of date with your code. Having a shared standard for describing your endpoints in a machine-consumable way. Being able to automatically generate typescript types from any schema (correct me if I'm wrong but I don't think there's any tooling that would do the same for arbitrary REST APIs). Being able to get autocompletion when writing queries for free ^ Those were all things I didn't know I needed until I started using them, and like Typescript, it feels painful to go back to not having them

You can write Swagger definitions to serve as contracts for your REST API. Swagger files are machine consumable and can be used to generate client SDK.