I'm curious how many web issues can be solved by having the people responsible for the relevant sites only be allowed to use them on a Windows 11 machine with only 4 GB of RAM using Firefox with the network throttled to 3G speeds.

Assuming the processor isn't horrible, I can still browse plenty of sites with those specs without much issue, and on the sites that do require more, it's very rarely because the sites actually needs it (i.e. I'm not running Windows XP in a VM in the browser or something). It could just be normal HTML and CSS and normal forms, sprinkled with some light JS to help out a bit. But the amount of sites made with that level of care and attention are sadly rare, since the people responsible rarely feel the pain or have the empathy to fix the problem.