Because that would likely be confused with compute shaders, which are not accessible in VRChat, we still regularly use geometry shaders, which as far as I know are just terrible compared to the alternatives.

The closest to compute shaders we have are camera loops using render textures and AsyncGPUReadback which has been limited to only handle inputs and outputs in the form of textures.

Also the reason why it is even done in shader is because the scripting language in VRChat is 200X-1000X slower than normal Unity scripting, with no async or way to do threads.

A programmable shader is the rectangle to the pixel shader's square, why expect the title to be intentionally vague about the constraints?