Good summary. It's best to think of controls like this as guardrails. They are mostly "safety" features rather than hard-core security features. They help honest people to avoid potentially dangerous mistakes.
Not sure what "support" you expect for unsupported clients.
It's definitely not true that this feature breaks support for devices not owned by the manufacturer. The follow on question about whether all possible web clients / operating systems would be supported, I don't know. The article just says that web is supported.
“Web is supported” in this instance just means “the web, but only when mediated by google, microsoft or apple”, which is not the web as far as I'm concerned.
They also can prevent honest people from gathering proofs to cover or defend themselves: abusive boss, illegal requests, harassment...