"How Chrome DevTools does it" was not my answer to the question, it was just the preamble. As mentioned, I much prefer to have caching disabled while I'm building or debugging sites (specifically: because I'm often changing the markup or the css or the javascript, and I want my most recent change to come through to the browser upon reload).

Because you don't want to disable caching of every other sites when you are not wearing your developer hat, just a "regular user surfing internet" hat.

Sounds like a case for using separate Firefox profiles, one for each "hat."

Why do that when I can just press "F12"?

That's not how it works. It only disables the tab you are working in.

This is exactly the point -- when you're developing a site, you want caching disabled on that site, but then when you're browsing another site just as a regular surfer you do not want caching disabled. Since generally when you're working on a site, you have DevTools opened, and generally when you're just browsing the web you do not have DevTools open, this is very nice.

I disagree with this:

> when you're developing a site, you want caching disabled on that site

I don't know why you say that. I only want caching disabled if I'm debugging something I think might be caused by caching.