Considering they made Chrome an entire OS… It was sort of necessary for that and probably minimal to bring it to the regular desktop browser.

That's both plausible and insightful on your part. Thanks!

That said, just because they could easily do it on the non-ChromeOS version of the browser doesn't mean they should have.

Chrome OS existed long before this API, it has a Linux base to handle this kind of thing.

it doesn't really need to, other than simplicity for the end user

Not being a jerk, trying to be succinct, but this is you missing or disregarding a crucially important point, in a dozen words.

As long as it's doable from userspace the OS doesn't know what's a browser or what is being controlled with external code. Blame the concept of ambient authority