YMC.exe is an executable exe file which belongs to the Lenovo Yoga Mode Control process which comes along with the Lenovo Yoga Mode ControlSoftware developed by Lenovo software developer.
Maybe that's why it is needed for your Yoga.
On Surface Pro 8 it was only needed to disable that registry variable.
I am still tho wondering the real differences in having the "Microsoft Surface 2in1 features" enabled and disabled.