I wouldn't be so condescending when talking about software development. I've got a CS degree and I'm a Machine Learning Engineer for more than 5 years. Pretty sure I know enough to contribute in such a discussion.
Nothing of what you have said shows remotely why the Slipspace Engine and Halo Infinite are build for the Xbox One. Knowing the money Microsoft put behind this game I'm sure they have two teams working on two versions of the game, both using Slipspace engine and both getting the best out of the prospective consoles.
Nice to meet you I am Artificial Intelligence Engineer.
So if you are engineer what are you talking about this? when you are designing a software are you able to dev a software which use in its 100% all your platforms available
even when in still designed in the year of your presentation, example make a software which should run in a FX-6300 in a decent performance while also your code
should use in the 100% the capabilities and features of the last ryzen CPU like use the set of instructions AVX, all of this while you already have a date to deliver and
your budget was assigned years before?
The answer is you cannot do it, because we just cannot spend and "infinite" amount time and money just reach that dream, so we have to make concessions, even
if you position you don't touch the code in so low level you should know that the people who is working with you and work in that part is who is in charge of make that decisions.
My logic is this one since the moment when start the design of that engine was years back before 2018, as we know when Phil Spencer
take the head of Xbox (2014), one of his first instructions was to created a machine which take again the crown of most powerful console
Xbox one X and was release until 2017, during this period of time Halo 5 was released (2015) and probably close to the 2015 the new engine
start is dev lest say 2014 during all this time until 2017 XSX was probably only in the mind of a couple of engineers of Xbox, also remember
they also need AMD actually have a GPU RDNA working man this was very after that year (2017) you 343 was already working in the game even before
AMD finished the RDNA or have it the Ryzen which happens until 2017.
You cannot go with your team and say people we change the way in how the are going to run some workflow because AMD came with the new ryzen CPU
so we need to create also a way of fully used, so please people of slipspace engine create a new API or libraries specialized for use the new set of instructions
and the came after the next year or two people AMD has the RDNA 2 please modified the engine for use RT to the max potential of the new GPU which still in
discussion for other team inside XBOX about the correct configuration of the SoC.
Is a miracle the games like Halo Infinite use some features of the new gen while still running in very old and obsolete hardware, think will use 100% in both sides
is dreaming with the open eyes.
Have two teams is a way to improve this but is not magically resolve the problem still exists and is not like both teams means one can change completely the mechanics
for use the new CPU and SSD at least they shouldn't, the team in charge of XSX and XSS has more limited time to designed,update or even create parts of the engine,
have two team means each team focus in each gen but not they will be able to do everything they want.