Perhaps HN could either do this automatically for Quora links, or simply prohibit Quora links that don't already have this added?

Given that Quora is in YC[0], neither of those things are likely to happen.

0: http://blog.ycombinator.com/quora-in-the-next-yc-batch

So, the Scribd treatment, then? (Scribd links were encouraged despite constant complaints about the difficulty of use relative to PDFs.)

To be fair, when the Scribd links were first implemented, 1) in-browser PDF was much worse than it is now; and 2) Scribd's interface was better than it is now. Over time, browsers got better at showing PDFs, and Scribd got more cluttered and weird.

I can't speak for others, but in my case, "difficulty of use" also refers to "you have to go through all these additional steps just to get to the document". I can't remember if that was only for grey-area, restricted-access postings, or if it applied to all Scribd documents, but I was conditioned to assume the latter by the time I saw them on HN.

> 1) in-browser PDF was much worse than it is now

Why would in-browser PDF support matter, when every platform has out-of-browser PDF viewers readily available?

Opening a PDF in browser is more convenient. That way the PDF behaves like another browser tab. Opening a PDF in an external viewer could be only one click and one alt+tab more, but it's less convenient and reduces usage. And it would leave one extra file in your downloads folder.

I recommend the "Quora Share" Firefox extension. It automatically adds share=1 to quora.com links:

https://addons.mozilla.org/en-US/firefox/addon/quora-share/

That would be great, in my opinion. For now I use an extension (though a Greasemonkey script would suffice).