Ironically, you provided an example of this: Lots of things can qualify as an HTTP client. FreeBSD's "fetch" utility and OpenBSD's "ftp" utility are certainly among them. Those are both parts of the operating system, developed by the FreeBSD/OpenBSD developers.
>> the "year of the Linux desktop" that everyone's been hoping will arrive for at least a decade
Everyone might be a little hyperbolic, considering that the majority of people are satisfied with OSX, Windows and/or ChromeOS. And there are plenty of other people who are satisfied with Ubuntu and Mint as their desktops. I would counter that the number of people waiting for the "year of the Linux desktop" is probably a small number.
And of course one can be satisfied with Ubuntu and Mint as desktops. It's just that when it breaks, you really have to know your way around the plumbing -- which end users don't.
For a huge swath of *nix users, Mac OSX accomplished everything they wanted from a "Linux Desktop" outside of being free and open source. That probably leaves a very small number waiting for the Linux Desktop.
FWIW, OSX is also unified, and requires little knowledge of the plumbing for end users.
Instead, the relevancy now mostly has to do with the unity -- or rather the lack thereof -- amongst NIX operating systems. While Linux dominates the server market, the "year of the Linux desktop" that everyone's been hoping will arrive for at least a decade now hasn't arrived. Sure, there are new challengers now and again but most of the problems and criticisms of Linux aren't about the look and feel, but usually fall on a more fundamental level: "Stuff breaks and then it's impossible to fix." -- "My audio drivers don't work and this tutorial to troubleshoot it is incomprehensible to me." -- "I took some updates and now Kdenlive doesn't export audio anymore."
Haiku is very different in this respect because its underlying architecture is the one thing Linux/BSDs are not and never will be: unified. The entire system, kernel to HTTP client to file manager, is developed by one team on one infrastructure inside one git repository. Which means as a result, you always know whose fault it is when something breaks (ours), and that when we fix it, it'll appear in the "nightly" update channel by the next day. It also means that there's no long series of configuration changes to try when something doesn't work; almost universally, stuff either works or it doesn't. Really -- there's only one exception to this I can think of (relating to a bug in our port of FreeBSD's Intel WiFi drivers.)
Linux has been trying for a more unified system both up front (e.g. elementaryOS) and in back (systemd...), but the more I use it, the less I want to use it and the more I want to use Haiku.