Everything not tied to the shader ALU's is faster, so ROPS run faster and TU's run faster. Command processors run faster. Caches run faster. etc. I don't know that being narrow in itself is an advantage though unless targeting a TF target.
Cerny's example explained it best. Given two hypothetical GPUs, one at 1 GHz with 2n CUs, and the other at 2 GHz with n CUs, both have the same shader performance measured in teraflops. However, the GPU running at 2GHz has twice the texture, ROP, instruction-dispatch, performance. Everything that's not shaders is faster than the wide, slow GPU.
However, if looking at cost, where we're possibly looking at XBSX and PS5's SOC being pretty much price comparable, wider and slower is clearly the more powerful option. It would appear that PS5's design was constrained by BC requirements after all, resulting in a forced solution as poopy as Nintendo's. Sony need a decent level of abstraction for PS5 game development to ensure next-gen, they have complete freedom over the hardware choices. MS on the other hand are already there, and their 'platform' is looking very robust going forwards.
