Here is the sad truth about Xbox.

They had a horrible Xbox One launch, yes, but that is NOT what really is killing their brand.

It's taking once great franchises and turning them mediocre. 

Halo and Gears alone are franchises that SHOULD always bring hardware sales up, but they didn't.

Gears 4 was okay, but not great. 
Halo 5 was a shit show (in terms of story, multiplayer was decent).

Gears 5 was so meh, I didn't even know it was released until 2021.

Infinite I had hope for, but it still was meh. Story and gameplay were better than 5, but still forgettable.

Long story short, Xbox never brought a game to the console that was worthy of the $$. Halo 1-3 all did this, hell even ODST and Reach would have moved consoles by themselves.

So the only reason Xbox is moving to multiplat is BECAUSE they can't ship a game that people would WANT to fork out the $$ for.

Spread a decent, but somewhat forgettable game across all platforms and it'll probably make money, but it won't ship hardware.

Sony, even though I don't care for the PlayStation, does know how to do this. Nintendo is the king of this.

Xbox is just the Disney of the Gaming world, where all the good IPs they have will be mediocre.