Principle probably doesn't come into play when the majority of people want to consume or share information in the form of text, video and imagery. Using Scribd or Youtube is very much a proof that people have found an easy way to share their information. It seems you're confusing "don't know how" with "aren't doing it while abiding by the principles they should have".
I agree with what you wrote yesterday concerning weights and measures. "Leave people to use what they want to use."
It's different though. Youtube makes possible what wasn't already possible - sharing video.
Sharing documents online has been solved for quite a long time now. It's easy (If slimy) to create a walled garden and coerce people into using it, but it'd be nicer to just show them how to share documents online.
Seems like the issue with Scribd is that it enhances the user experience for average user, but for techies/early adopters, it makes for a far worse experience than the alternative.
How would you explain to a non-technie writer (with no knowledge of HTML or web hosting) how to share their word or pdf files? Seems whatever solution you come up would probably be similar to Scribd.
I agree with what you wrote yesterday concerning weights and measures. "Leave people to use what they want to use."