There's some virtualized desktop server stuff too. Run a bunch of desktop sessions on a beefy computer and send a video stream to desktop players. With the right codec settings, the latency is probably ok for many games.
I'm sure manufacturers would love saving a dollar per card, and OEMs would appreciate eliminating the support calls from "I just bought a new $2500 gaming PC and no video" because they plugged the monitor into the iGPU instead of dGPU.
Thinking about it more, on my setup I have a DVI port on the motherboard that I would be happy to use with a DVI cable, but I instead need to buy a DisplayPort <-> DVI converter cable to plug directly into my video card...
Yeah, seems like an obvious thing for some motherboard providers to want to provide.
nVidia has also used the datacenter cards to run GeForce Now, at least for some lines of the cards, plus some of them come with license (or you can buy it extra?) for nVidia GRID that provides more flexibility for multi-instancing etc to run in virtual desktop