The [very] successful process of developing the Linux kernel with nothing but git, mailing lists and a small set of simple rules (no meetings, no Scrum, no BS) proved to be good-enough.
It is not only Linux kernel, there are hundreds of other "decentralized, no-water-fall" projects, notably FreeBSD, OpenBSD, Xorg, LLVM, Golang, CPython, Ruby, you name it.
It is much better to consider the differences between a commercial organization (a corporation) with all that bureaucracy obsessed with keeping its positions and budgets, etc. and a team of enthusiastic professionals with their own "inner" motivations and goals.
Corporations are producing products to make profit, while teams of enthusiasts are producing (evolving) tools and services for themselves.
The difference is the same as between McDonald's and family/home-made-for-themselves food.)
Consider, for example, LLVM/Clang (backed by Apple) as high quality and no-cost alternative to VS. Its used as a primary compiler for OS X, iOS and FreeBSD and optional one for Android NDK.
And, look ma, no bureaucrats, no meetings, no Scrum.