A well-known advantage of PDF is that it pretty much assures I can save a document, share it, move it around etc and it will still be intact and readable. That's one of the reasons it's so popular.
Mostly we don't do that with HTML. Mostly we just point to it. But if I see an article these days, I want it on my computer if I'm allowed; this let's me study it at leisure, drop it in my Mendeley system, etc. As pointed out, that works a treat with PDF, and pretty well with Word or OpenOffice documents as well. This applies even where the document is quite heavily compound, with many embedded images, tables etc.
But if I try saving a HTML document to my hard disk, nothing very standard happens. OK, if I use Safari on my Mac, I get a .webarchive file, which is quite nice as I can do all the things with it that I could do with a PDF and Word etc, and when I open it later it will be as it was before, with all the images in place. But neither IE nor Firefox seem capable of opening a .webarchive file.
If I try saving the same article from Firefox, I get a .html file with the main article in it, and a directory with associated files in it (eg images). Safari does seem capable of opening this combination, but it's pretty ugly, and hard to move around. I haven't tried IE as I don't have easy access to it.
Is there in existence or development a standard approach to packaging the HTML and associated files that would be as convenient as the .webarchive, but usable across all browsers? If so, Scholarly HTML would be that little bit closer!