The difference is that uBlock Origin is an extension you intentionally trust and install, while the JS API we talk about are something any websites (untrusted) can use.

To be fair, uBlock Origin has always been a special case. It's so good and so important and so trusted that it should have access to browser internals that normal extensions can't access.

Honestly, uBlock Origin shouldn't be an extension to begin with, it should be a literally built in feature of all browsers. Only reason it's not is we can't trust ad companies to maintain an ad blocker.

Perhaps the users should be given an option to opt out (enabled by default) for such APIs on a per-site basis. That way, users can intervene when they're abused, while their fair use will remain transparent.

This seems like a good compromise. Similar to requesting location information, and/or denying popups after a few have been spawned

How is uBlock Origin "doomed" ?

An advertising company controls the user agent everyone uses to access the internet, and wants to shove more ads into your eyeballs. uBlock exists as long as they allow it. Anyone who disagrees with this, works for them or own shares in the company.

So UBO isn't doomed, just UBO on Chrome. While that's significant given Chrome's market share, I and everyone else on the planet have the option to use something else, and will continue to do so.