I’m not too familiar with AMD/XSX architecture, but why wouldn’t ROP scale with number of GPU cores? Why would MS design something with lower ROP/core? Also, where did you get these details from?
Since compute shaders can write out directly into memory you don’t need to use the ROPs to write the result into a buffer / texture like in the early days of GPGPU.
If you assume 20-30% or even more of your frame GPU budget is spent on compute you can reduce the number of ROPs to match.
Unless you have other bottlenecks you really only need as many ROPs as the fill rate you’ll be targeting which will be dependent on the resolution and targeted frame rate.
10-15 years ago ROPs and TMUs scaled 1:1 with GPU “power” the more you moved the load into shaders and then compute the less meaningful those figures are.