The original comment said "One of the biggest selling point rarely come up is that you get the API docs for free" while comparing it to Swagger. Both GraphQL and Swagger gives the same ability to generate API reference documentation.

So how is that the "biggest selling point" of GraphQL when it's not even new in the ecosystem?

Because swagger docs are defined via proprietary yaml definitions whereas graphiql exposes a more useful interface that is actually derived from your code, which in most cases is automatically generated from your DB model.

I've written a lot of swagger docs over the years, GQL is a massive improvement.