However I don't think it's a given that it will be prompted by Google, or will continue to be the case.
Google is an advertising company. Android, does not make money through licensing. It makes money by being a vehicle for advertising. Apple on the other hand, make money through selling products. Advertising (on the web) shouldn't make much difference to them, and helps put pressure on the competing platform as well as Adblocking being a potentially valuable feature to help sell their products.
How? I can't install plugins into my Chrome on iPhone 6s.
And you can't switch the default browser so it only helps in 30 % of the cases (when you are not inside Facebook/Twitter/etc and when you are not clicking a link that opens the default browser)
However I don't think it's a given that it will be prompted by Google, or will continue to be the case.
Google is an advertising company. Android, does not make money through licensing. It makes money by being a vehicle for advertising. Apple on the other hand, make money through selling products. Advertising (on the web) shouldn't make much difference to them, and helps put pressure on the competing platform as well as Adblocking being a potentially valuable feature to help sell their products.