It’s a good, standard protocol with unreasonably low adoption because of the chicken and egg problem between mail providers and mail applications. If Gmail supported jmap it would encourage implementers everywhere to support it. And jmap supports notifications and all the rest.
I agree, but why would Google adopt it when they have their own proprietary protocol with similar functionality? Companies love anything that makes them more "sticky", whether it's good for the user or not.
It’s a good, standard protocol with unreasonably low adoption because of the chicken and egg problem between mail providers and mail applications. If Gmail supported jmap it would encourage implementers everywhere to support it. And jmap supports notifications and all the rest.