The benefits are that, you don’t need to be on a specific version of anything to make this work properly.
For what it’s worth, flatpaks do share dependencies as much as possible. So that inflated size isn’t going to be replicated for each application.
Also, flatpak _is_ a proper distribution. It doesn’t really do anything fancy other than isolate the dependencies from other tools on your system.
Flatpak doesn't solve the dependency problem, it just kicks the can down the road.
We need better tools to package and deploy apps that's language and system agnostic, and an easy to use extension system to accommodate this.
Nix is the first package manager that actually gives a proper solution, and it is just much much better and has no space overhead either.
The benefits are that, you don’t need to be on a specific version of anything to make this work properly.
For what it’s worth, flatpaks do share dependencies as much as possible. So that inflated size isn’t going to be replicated for each application.
Also, flatpak _is_ a proper distribution. It doesn’t really do anything fancy other than isolate the dependencies from other tools on your system.