I cant count the number of times I had to take screenshots to save crucial information from web pages.
Yes but for my use case, which is better scientific communication means, PDF is not enough.
Consider for example slides for a presentation. The typical mathematician does them in TEX which outputs a PDF. Then the PDF is (sometimes) made available online. I realized that PDF slides are far inferior to HTML slides (where you can add demos and whatnot, shameless example ). Just put all in a github repository and anybody can take them home.
I use now "SingleFile", a Firefox or Chrome extension that helps to save a complete page (with CSS, images, fonts, frames, etc.) as a single HTML file.
MHTML exists. https://en.wikipedia.org/wiki/MHTML
However, it does not work if what you want to save is not a wall of text. Some table, some receipt, etc. It does not work for the Google search box, for facebook, or Amazon, just to give an example.