Then, there are things like head tracking which are either another dedicated peripheral which may or may not get drivers, or a set of apps which feed from a webcam and output the signal to a standard driver that games know to check for.
Finally, most 3rd party add-ons have custom installers, and I'm guessing most of them won't have a working Linux version. So, while I'm sure it's possible to run, say, a vanilla X-Plane on a non-Windows installation with no peripherals/apps/add-ons, I just see a mountain of work to get a normal, heavily custom installation working.
I know that this isn’t an easy solution/doesn’t go against your argument, because it isn’t download-and-run simple, but discord’s version can be modified with no consequences in a build_info.json file. I used to do it manually, back when they updated it every once-in-a-while, but due to their current tendency to push updates every few days or so, I’ve made a few-line bash script to fetch the latest version (thank you httptap) and patch the file for me. For screen sharing, I use whatever current discord client on GitHub supports it for Wayland, which usually has the added benefit of not limiting quality and framerate options.
But yes, you do have a point, it’s not just ‘as simple’ as it is under Windows - when Windows works properly.
It Just Works.
The package system is very important to learn in Linux. People have 12 ways to install an app, and they are far from equal.
Think about it from the POV of a Windows user, especially one who has never used Linux before, and especially one who doesn't know what HN is. To install a program, the first thing you're going to do is type "discord" into your browser, and go to their website. Discord's website doesn't suggest that there's a better option. It just gives you a DEB file.