There is also no one canonical linux stack. Different distros do things differently (sometimes drastically so).
E.g. systemctl flags and argument ordering differs from sysv style /etc/init.d/foo commands (as just one example)
So to learn “GNU/Linux” really you need to learn several distributions and piece together the common components and why different approaches are better suited to different environments.
Does this fragmentation help or hurt the ecosystem over the long-term? I personally think it's the #1 reason Linux never stole any sizable market share from Mac OS X/Windows. Hardware support just isn't there. Polish just isn't there. Instead I can name multiple init systems, multiple shells, multiple package managers all fighting for space in our "brains" to be remembered and used. :P
If we really want good hardware support on Linux we have to at least some reference that manufacturers can use to verify it works
The problem for hardware manufacturers is that they think their drivers are valuable trade secrets and don't want to mainline them into the kernel...
Again, this is by design to try and force manufactures to open their driver code. To me, that seems like a lost cause now thanks to the proliferation of binary blobs required for hardware anyway.
> So, if you have a Linux kernel driver that is not in the main kernel tree, what are you, a developer, supposed to do? [...] Simple, get your kernel driver into the main kernel tree (remember we are talking about drivers released under a GPL-compatible license here, if your code doesn't fall under this category, good luck, you are on your own here, you leech).
In order for a driver to be in-tree, it has to be open.
Incidentally, this document is full of the kinds of arrogant and user-hostile arguments that the Linux community is known for, for example: "You think you want a stable kernel interface, but you really do not, and you don't even know it."
The bad manufacturers like Nvidia and Broadcom intentionally block Linux compatibility for drivers they don't write themselves.
I assume you speak about desktop. MacOS never had any huge market share in this space. Its iPhone (and its predecessor, iPod) which allowed Apple to become as big as they currently are.
> Does this fragmentation help or hurt the ecosystem over the long-term?
Over the long-term it allows for abstraction layers, such as Ansible or Nix, to become status quo.