It's alpha. Of course not.
But the fact that is has one at all, is an improvement over GNOME where the plugin "api" is just javascript injected into the main gnome shell process.
The main reason why System76 decided to build Cosmic in the first place was to avoid having to spend an inordinate amount of time (I heard 50%) fixing their extensions any time Gnome made a new release.
The fact that they were able to release this alpha of Cosmic DE in one year just goes to show how much better a use of time it is.
