The last part is essential, because GitHub LFS is too expensive for anyone to just try out on their own.
But then, on the dev tool side, we would need automated ways to get all that stuff in the repo in the first place, and make sure that the IDE linting and autocomplete knows about it.
I used to put my python dependencies in a thirdparty folder, and have a line that alters the sys.path to point at it.
I just spent a week getting rid of all that and using PyPi, because it didn't play nice with linters and I couldn't swap different versions of dependencies with virtualenv, updating required manual work, and there was no management to make sure there wasn't version conflicts in subtle ways.
I like the idea of deps in VCS, but not as much as I like using tools as the devs intended and sticking to the official workflow everyone else uses.