I'd love to hear the details of why web developers like this feature? As opposed to say, clicking through the various dimensions in the responsive design mode? I guess the idea is seeing the changes live: So as you're fixing one aspect ratio, make sure you're not simultaneously breaking another?

If you're using something like Webpack, that supports hot reloading, couldn't you simulate this just by having multiple browser windows open, each displaying a different dimension size? So then is the idea that having to set that up manually each time is a pain?

(Not judging, just seeking to understand, I'm a huge fan of any kind of speed increase, but I'm curious if I'm missing anything here.)