I thought the length of board traces were part of the reasoning against that idea.
If you could have your CPU placed symmetrically in the middle of the board with slots, ports etc both above and below so they don't get too long traces then maybe? But that would go against the ATX spec.
I also wonder how often communication happens from one device direct to another without touching CPU? Is that a thing? DMA has been a thing for many years but with the memory controller on the CPU communications would still have to get there.
If you could have your CPU placed symmetrically in the middle of the board with slots, ports etc both above and below so they don't get too long traces then maybe? But that would go against the ATX spec.
I also wonder how often communication happens from one device direct to another without touching CPU? Is that a thing? DMA has been a thing for many years but with the memory controller on the CPU communications would still have to get there.