Because Microsoft has had a history of caring about privacy?
I'd expect something like this from Apple with Safari, but not Microsoft. M$ can't even give its own developer base privacy by allowing all telemetry to be disabled.
Companies don't care about jack shit. Tim Cook doesn't "believe in" privacy, he thinks it helps sell devices (and that lack of privacy could lead to scandal that would hurt sales).
Whether one company is effectively more private than the other has nothing to do with what the company actually believes. It doesn't really matter what they believe. When you compare the two companies, Microsoft arguably has a greater history of embedding tracking in its products than Apple. This isn't to say that Apple doesn't track anything. As far as I'm aware, Apple didn't help the NSA bypass encryption or build backdoors into its OS.
I'd expect something like this from Apple with Safari, but not Microsoft. M$ can't even give its own developer base privacy by allowing all telemetry to be disabled.