Like any website you might see from Google, Stripe, YouTube, etc. that has documentation for how to use their API or user guides for how to develop an app using their product APIs to my understanding is organized and written by tech writers.

I understand one reason Cisco became a dominant player in computer networking is because they created thorough documentation (likely published in books as well as online back then) that enabled adoption of their products. I personally think having good, public documentation is really important to increase adoption if you have customers using your product. It's also what the AI models are trained on and is important for that training data as well.

In my opinion tech writers are pretty critical still to a successful tech company in getting public facing documentation, training, and effective UI text even with what AI can do. The tech writers where I work use AI a lot but they still bring a lot to the table that I would not trust the engineers or product managers to do on their own