> NetBSD's main claim to fame is that it runs on practically everything

That means available number of architectures. NetBSD still support some pretty esoteric stuff, but though I haven't actually counted I would expect Linux to run on a comparable number of architectures.

Now, the kernel will probably boot successfully on a given machine, but whether hardware (i.e. driver) support will be decent enough for everyday use is a completely different matter! For example, NetBSD "works" on this laptop of mine... except for Ethernet card, Wi-Fi card, touchpad, ACPI suspension, external monitors via the docking station, ... :)

I'm trying (for fun) to bridge some of these gaps, but you can see how this isn't appealing to the average user.

The impression I get is that NetBSD has just enough code to get it up and running on a machine but there is not enough development and testing to get it to run well on a machine.

As a NetBSD developer, I wouldn't claim that it works on everything.

Depends on what you mean with "it runs". Does it boot? Probably. Can you use your WiFi adapter or graphics card? Probably not

That was true 20 years ago, but not really today. Today's hardware is much more complicated and I wouldn't expect NetBSD to work well on anything but the most basic hardware.

"runs on practically everything" I take to mean the main CPU and general machine architecture, not every possible peripheral driver one might need.