It does work that way.

Otherwise, we’d all be running a stripped down Clear Linux kernel, BusyBox, and a few tool chains.

I'm not sure what point you're trying to make. If performance was strictly dependent on features, as you say, then we would be running an extremely stripped down OS.

But it's otherwise, and no one does it, even those who care about performance (removing excessive services notwithstanding).

The point is people take trade-offs for performance vs. features. Features take up some measurable amount of performance.

It's a sliding scale, but everyone sits on that scale nonetheless.

Absolutely correct. There's a reason that Linux servers (and even some versions of Windows servers now) don't run a GUI, for example.

You got it in reverse then.

Last time I checked, performance was one of the benefits of the GNU environment over BusyBox.

Also, a lot of the features on the Linux kernel are there specifically to improve performance.

Plenty of features get in the way of performance. Or are you suggesting we should ditch animation, modern font rendering, file metadata, all permissions checks, most low level security features (ASLR, stack protection etc.), Spectre protection, high resolution displays, USB, frequency stepping, etc. etc. etc.