It's The Register being pedantic and a bit argumentative.

There's a reasonable argument that Chrome OS is Linux--or at least more so than Android is. But it's not so much that it's "the wrong kind of Linux" according to purists as the article says but that it mostly addresses a different use case than installing Fedora or Ubuntu and therefore, IMO, it generally makes sense to treat them separately unless your point is that Linux (and *nix generally) has a pretty large market share on both desktop and mobile.

I'm not sure it addresses a different use case than Fedora or Ubuntu. Fedora and Ubuntu on the desktop are likely mostly used for internet browsing and productivity applications. This is the same for ChromeOS.

The ChromeOS use case is a strict subset of the use case of a normal Linux laptop. There is nothing stopping you from treating an Ubuntu installation as if it's as limited as a Chromebook. It's every bit as lightweight and can be every bit as locked down.

> can be every bit as locked down

I've never seen the security stuff from ChromeOS be ported to live outside of ChromeOS. When I looked at it (trying to build the inside-container agents for acustom container image), the error messages for setting it up incorrectly were.. let's charitably say hard to understand. I doubt anyone outside of ChromeOS developers understands it, really.

It's pretty intricate, e.g. giving Wayland access to virtual machines in a safe way.

I feel that it could have been made clearer by writing "GNU/Linux has nearly half.. [etc..]", maybe?

That's not a joke though and the whole point is made with the weird title

But ChromeOS is also GNU/Linux

No, that would exclude Alpine and I don't know any purist claiming that Alpine isn't Linux.

Pretty soon, SteamOS will be separated out. Then Linux will makeup an even smaller portion of the "desktop Linux market."