Publishing extensions on Chrome/Firefox is annoying, and we probably would have more extensions if it was easier.
But, it's not so annoying that the entire platform is being abandoned. This is a matter of degree, but there's a point where the effects of that annoyance become very obvious.
If publishing on Apple devices was just a tiny bit more annoying, devs would complain and then still publish their extensions. But that doesn't seem to be what's happening, it seems Apple has crossed a line where extension devs have decided to just ignore the entire thing.
But, it's not so annoying that the entire platform is being abandoned. This is a matter of degree, but there's a point where the effects of that annoyance become very obvious.
If publishing on Apple devices was just a tiny bit more annoying, devs would complain and then still publish their extensions. But that doesn't seem to be what's happening, it seems Apple has crossed a line where extension devs have decided to just ignore the entire thing.