The Swagger/OpenAPI spec format is its own special little hell. Just enough "user friendly" features to make it difficult to parse, yet still complicated enough that it's a pain to write.
I personally prefer API Blueprint, but even there is room for improvement.
It’s strange to have been playing this game long enough to see a full cycle.
Here be dragons.
Furthermore, with an http api and depending on your security model, you can test/inspect a good portion of your APIs directly with a browser - a zero-cost client for all http apis that you get for free.
It might be a benefit of statically typed languages though. I have no idea how you would automatically generate swagger from Javascript, without adding so much annotations that they become a poor man's types.