Microsoft and Canonical partner to bring Ubuntu to Windows 10

The POSIX subsystem was so crippled that it was unusable (no graphics or network). SfU was neither free nor included by default, except for one free version which also happened to be its last. Also at those times Linux did not have the market penetration that it currently has with Android.

Right. As I've heard it, the POSIX subsystem was essentially a checkbox feature to meet some government contracting requirements.

You confuse the POSIX subsystem with SFU/Interix (originally called "OpenNT", but soon renamed to "Interix". Later bought by Microsoft and rebranded as "Services for UNIX"):

> https://www.samba.org/samba/news/articles/low_point/tale_two...

> http://brianreiter.org/2010/08/24/the-sad-history-of-the-mic...

I specifically remember that I read that (it was a checkbox feature) about the ancient POSIX subsystem. The SFU/Interix system was a bit more capable, I think? I did install it at one time, but never really used it.

Edit: yes, that is in fact exactly what the first link you gave says: The POSIX subsystem was added as the POSIX standard had become very prevalent in procurement contracts. [...] This original subsystem was, I think it's fair to say, deliberately crippled to make it not useful for any real-world applications. Applications using it had no network access and no GUI access, [...] SFU contains a full POSIX environment, with a Software development kit allowing applications to be written that have access to networking and GUI API's.

What I heard was that they took advantage of every function that could technically be "implemented" by setting errno appropriately and returning an error value, rendering the subsystem useless while still allowing the box to be checked off.

I remember trying to use the Services for UNIX Version 1.0 Korn shell for a job. Coming from bash/zsh, I loathed it. I opted for Cygwin's bash ASAP.