> this strikes me as a very specific brand of 1995’s prose, spanning about 30 years.

It's probably a fair approach to say the significant influence (training dataset) on writing at a particular time is the preceeding 30 years' material? It's certainly not only what's already written that year (nor anything since).

Had to pick a year, and most of the material hovers around the mid-90s, the golden age of MS docs. And 1995 is THE Microsoft year. :)