Name a native UI framework that enables seamless cross-platform deployment without extensive testing on each platform.
Go ahead, I'll wait.
Go ahead, I'll wait.
Meanwhile, Microsoft is a behemoth. Your argument makes total sense for a small shop with limited bandwidth to test. Companies like Microsoft don't get that excuse. They're simply padding their bottom line at our collective expense, and they can do it because they have extremely sticky services in a lot of areas (in this case, corporate email infra).
Same goes for Android/iOS.
These new Microsoft applications run on all these platforms identically across all these platforms and mostly with the same code.