8 channels of DDR4-3200 only provide 200GB/s bandwidth. RTX 3090 has 936GB/s. So even 4 socket Xeon won't catch up.
Many if not most other algorithms are iterative. Hell, even sorting is.
GPUs are like heavy flywheels. Getting them up to speed takes some time (copy data, compile and copy the kernels, kickstart everything, etc.), so you need to start them once to get the performance benefits. Otherwise CPU is much more nimble since they're closer to RAM and made to juggle things around.
I guess it's time to invent a blockchain that trains ML models as PoW :)
As a sidenote, I have rented servers with GeForce cards from multiple providers in multiple countries, so this rule doesn't seem to be respected very much. And since it's part of the driver EULA, nvidia can't legally go after server providers, since they don't install any drivers, just build and rent out the hardware. For all they know, all their customers are running noveau.
[0] https://www.datacenterdynamics.com/en/news/nvidia-updates-ge...