My old employer used to have people on staff just for technical writing. Some of that writing became the man pages you know, and some of it was ‘just’ documentation for commercial products - ID management and the like.
Then we sued IBM for breach of contract, and if you ask anyone about it they’ll parrot the IBM PR themes exactly, as their PR work was brutal. People in Usenet and Forums were very mean, and the company decided to stop offering much of the stuff that it was for free. It was very ‘f this’.
If man pages needed a volunteer to maintain, I know why ours tapered off.