Earlier quoted context omitted.
Git has submodules too and teams usually have access control on the main server used for sharing commits.
git submodules aren't seemless. None of the alternatives appear to be any better. A halfassed solution is no solution at all.
I can imagine that part of it could be the need of a git clone --recursive, and everybody omits the --recursive if they don't know there are submodules inside the repository. There is another command to pull the submodules later but I admit it's far from ideal.