> By 'platform', I mean

You mean Linux distributions.

> From that perspective, even purely user-mode applications that ship with the distro ought to considered 'platform'.

Every Linux distribution is its own platform.

You decried Stallman's meme rant yet you just rewrote the entire rant in your own terms. Linux is the kernel, GNU's just the stuff on top. You can get rid of it if you want and make your own. Android did exactly that.