Linux

You still need base CPU speed for a system to be usable. Try running a modern GPU on a 10 year old CPU. It's even worse for some, where the GPU driver needs a relatively fast CPU for the GPU to run at full speed. Mostly Intel GPUs have this issue, which is sad cause they are the most affordable, but can't be paired with an just an affordable CPU (or an older one).

And we're very far away with RISC-V from the kind of performance your need to run modern games, or even decade old games. Let alone fully utilizing a high end GPU.