A Mozilla employee recently released a Firefox addon to change the user agent to Chrome on sites the user enables it on.
You shouldn’t have to do this. I blame W3C org and their ilk for putting the rendering engine, browser brand, and browser version in the response header. All your browser should be telling the site is the versions of html, css, and JavaScript it supports and whether it’s mobile or desktop.
versions of html, css, and JavaScript it supports
Given the level of support a browser has for something is basically the browser’s version (there’s no such thing as a version number for JavaScript or CSS for example, there’s a spec that’s kinda versioned, but browsers don’t implement everything the same), you’ve basically just described user agent strings
We have feature detection approaches today that make UA based browser detection generally unnecessary but the horse has already bolted on that now
The evolution of the user-agent string isn’t exactly the W3C’s fault.