In my mind, the part that is most likely to fail is "return an HTML document that still contains the following text." Nowadays, more and more "HTML documents" do not contain any content at all, just some JavaScript that is responsible for then fetching and displaying the content.

I used to be someone, man, I was a dreamer, a programmer, a man!

Now I'm a human slave copying text from web browsers to chat windows to get around JS rendering bullshit.