The person said "containers" so I was responding to both.

However, docker containers could stand to learn a thing or two with how flatpak and snap compose a runtime. Applications can say "allow x, y, and z dependency layers to update independent of the application container", versus the docker style of the app developer must own maintenance of the entire image.

There may be reasonable differences with respect to how much of a users "real" files and environment are presented to a container in those scenarios, and functional differences like gui and networking suggesting different defaults,, but image composition does not need differentiation for their use cases.