I know all that you wrote. I have been working with Unix since the early 80s. I am fully aware of what you pointed out.
I just meant that the distinction between Linux and Unix nowadays is so minimal that is it meaningless, when discussing functionality as a desktop OS to an end user.
In the server world, there is a distinction, with difference. But we were talking Windows desktop replacements here, not server OSes.
(As an aside, I am not a rabid Linux supporter. I prefer the BSDs: NetBSD, OpenBSD or FreeBSD. Much more complete, coherent systems than your typical Linux distribution.)
This is the only thing you wrote that I might take issue with.
Ref: I've used NetBSD, FreeBSD, Ubuntu, and CentOS/RedHat extensively for 20 years (in the case of NetBSD) and 16 years (in the case of RH). I currently use NetBSD where I need a high-security network OS, and Ubuntu as my desktop OS.
I would not trade away Linux for any of the BSDs, on the desktop. Unix is nowhere near as widely supported by application vendors, meaning you're dependent on compiling your own applications, which I do these days only when necessary. Apt and yum are miles ahead of raw pkgsrc, much as I enjoy rolling my own at times. So I would hesitate to call Linux and Unix indistinguishable -- to a typical desktop user.
But to each their own -- that's the beauty of free and open source software, after all. :-)
FRegards, dayglored