Some would disagree.
Point is it's a matter of opinion not cut and dry when discussing exclusives.
There are multiplat games where Series X shows an edge, recently Mortal Kombat 1 runs at a higher dynamic res than PS5 on XBSX, and Immortal of Aveum ran ~10 FPS better at points on X (relevant more for being one of the first UE5 games). These are just two that come to mind, it isn't like Xbox doesnt have it's wins, as many as PS5. It just seems where X has an edge it's talked about less.
Also I think it stands to reason, PS5 has higher clocks. On older rooted games that dont stress shaders, which lets be honest is most all of them to this point, it's faster I/O might be expected to win out by a bit. OTOH as games get more advanced and complex farther in to the gen, and more math bound, Xbox could stretch it's legs. The thing is development is so molasses slow now, that who knows when "next gen" games proliferate, year 6?
Then you get into the fact Ps5 has at least a 2:1 worldwide install base edge. As such it's the lead platform, nobody is going to design around 20% more flops on Series X. There's countless factors that could dull the paper edge. I suspect another one is development environment, wasn't there rumors it was worse on X?
Yet ALL THAT SAID. I would agree XSX has not really shown it's paper power edge to date by and large. And that's disappointing. Even if the above factors can help explain, and 15-20% in math parameter may not be huge to being with, when at a fill rate deficit etc.
But I'd be interested in discussion if the split RAM speeds did harm XSX theoretical. Gotta be some devs who know... but they'd basically be the only ones, hands on devs, and it's very hard to find them or get them to talk.