Except there are a lot of people who are exactly the opposite.
I love Dura-Ace on my Road Bike, but for Gravel and MTB I wouldn’t touch Shimano. Even the MTB Groupset 10-52 is fine on my 1X Gravel Bike and I have zero issues with the gear spacing even when using my gravel bike on the road.
And, Shimano Power Meters suck, to the point where I have a Quarq PM and SRAM Red crank on my Dura Ace Road Bike. So, it actually is possible to mix / match in certain scenarios.
And who knows, maybe they’re banking on new Shimano releases or a more accepted standard…