Individual frames as separate images would be an interesting idea but, if you like to get weird with your panel shapes/sizes or overlap them a lot, then you'll risk a really messy-looking vertical stack for mobile screens. If you tend to use a lot of white space in your pages, then spacing the panels out on a large screen would be difficult. And that's not considering how annoying it would be to draw a page and then try to export anywhere between four and ten panels every time. But then, I draw everything as it will print. The pages read well enough on my phone, so I don't worry too much about mobile as long as my websites work.