I find the article slightly confusing, but what I believe the author wants to say is that special-purpose machines allow for better optimization than having to

I find the article slightly confusing, but what I believe the author wants to say is that special-purpose machines allow for better optimization than having to support a wide variety of generic hardware. So in effect, this is the same argument as game consoles vs. desktop PCs. Every PS5 game can use primitive shaders, because the developers know that every PS5 will have them. For a generic desktop PC game release, though, only 1% of all buyers will have a new enough AMD RX Vega GPU, so it doesn't make sense to invest much resources into supporting primitive shaders there. That said, pretty much all of the specialized hardware that Workstations used to have in the past is now commonly available everywhere as vertex, compute, or pixel shaders. So in my opinion, the workstation marked died because suddenly everyone gained access to what was previously reserved only for workstation users.