While the capability for running extensions on mobile chrome has always been there and is quite evident with the chrome forks like "Kiwi browser" which runs every chrome extension including ublock just fine.
It only shows how Google must have deliberately decided to purposely never support extensions on mobile from day one.
I mean it's much harder to give something and take it back, so you generally phase out functionality out by citing security issues and that's what I think is this whole v3 fiasco is all about too.