The XSX was an after thought because Phil Spencer got high on his own supply and believed Sony would release a low-powered console with similar spec to the series S. That's why the series S is 'better' designed with more aesthetics than the S.
However, it was a sneaky bit of corporate espionage by Sony; they told some devs they were making a weak model and wouldn't release full specs until very close to launch.
When MS found out about the real specs of the PS5, which are genuinely impressive, Mark Cerny is a genius, Spencer et al shit their pants and needed to make a console more powerful than the PS5, and NOW!
So they jammed a load of off-the-shelf components together and threw them in a box. The first gen XSX were over-heating because 0 thought went into cooling or how it would work. Which is why, despite being more powerful on paper, the XSX runs games like dogshit.
The real funny part is Spencer released his twitter bots saying the XSX had RDNA 2 and PS5 only had RDNA1, which was a lie. AMD and Sony (mainly Cerny) collaborate on innovations and gave MS the off-the-shelf RDNA2 GPU, while Cerny custom built his chip to take bits of RDNA1, 2 and 3 (unreleased at the time) to make a far superior GPU to the XSX.
MS are buying the software because Sony, for all of their retardation, kicked their arse in the hardware department - the only part of Playstation that's not retarded, again thanks to Mark Cerny, the last old-school tech geek still giving a fuck in the industry.