You are not a great listener Riky but at some point the penny needs to drop.
Let's be nice and state that the XSX and the PS5 has so far on average performed equal across a fairly ok sample of cross-generation titles (as stated it has been very close between the two but actually a small edge - so far - to the PS5).
On paper the XSX has a more powerful GPU. Where did that power go? Are Microsoft that bad at hardware design? Of course not. The answer is actually exactly what you are eluding to above. The XSX has dual speed memory for only one reason - that MS wanted the same board to be used for the server blade as for the XSX which resulted in the same memory controller silicon but with slightly less memory on the XSX than the server blade). Same goes for the largest shader arrays of any GPU ever - if MS only needed to design the XSX they would not have been that large since it will result in intermittent bottle-necking of the array.
MS made these choices to drive down the manufacturing cost of both the XSX and the server board - at the same time as ensuring hardware based back-ward compatibility.
That is one of the main reasons why you more or less see parity between these two systems.
That's one interpretation of their choices, but it's not the only one and not what the people who designed the machine say.
They said the "split memory" which isn't actually split in the traditional sense of the word is down to developers asking for faster optimized Vram, since say Valhalla on PC only uses about 6.5gb and that's the most I've heard of so far then I seriously doubt it's a problem, maybe it takes more work but that doesn't make it a bottleneck. I've got a PC with 8gb of Vram, I've never seen it get anywhere near that.
As for why Xbox hasn't shown an advantage in every game well traditionally that hasn't happened in previous gen, there were occasions PS2 outperformed Xbox, Xbox One on PS4 etc, it's not unheard of, that didn't make the PS4 or original Xbox badly designed.
My take as I've explained before is that the games so far have all started as last gen games, to get ready for launch and to mitigate the problems of working from home Devs have taken Pro and X1X versions and upgraded them for next gen, just because a game released after the new consoles doesn't make it next gen.
Xbox has had a bigger change in developer environment and if you look at the specs of going from Pro to PS5 in compute units etc it would be a lot easier to port and unlock extra performance where on Xbox you have a different setup of memory and a wider GPU.
Once we had a game that's wasn't rushed for launch in Hitman 3 then Xbox had a big advantage at 44% resolution advantage and higher shadow settings, a bigger metric than the paper metric .