Turns out that Web Environment Integrity proposal everybody is getting angry about (imo very legitimately) was effectively already shipped by Apple in Safari last year
That’s irrelevant. This proposal only gets bad if enough browsers support it that site owners can tell everybody who doesn’t use it to leave. At that point the open web is dead.
Which is also what the article is arguing. As soon as a majority of users are subject to this the websites can discriminate. If only safari does this it's still bad but not very bad