The problem with PDFs as web content - it is easy for authors but hard for visitors.

"The thinking behind posting PDFs on websites is completely understandable — everyone wants their job to be easier, and everyone wants their website to be as useful as it can be with as little time/effort/training/expense as possible. Click the little 'PDF' icon in Microsoft Word and what’s next?

Unfortunately, punting to PDF is only easy for you; it shifts the effort to your visitors. Other people are just as busy as you are, and if you force them to invest the time to sort out your publishing issues, I just don’t care is their most likely response.”

This quote is from Christopher Mackay’s excellent article Publishing PDFs: a web content microcosm | Tantramar Interactive Inc., December 2014.

In the article he highligts four ways friction is introduced into the user experience when a pdf document is added to your web content. He also describes the solution

“The way to make a site easy to use is by sweating the details; it’s a lot of hard work. This battle is fought every day in the trenches, where people ask themselves is there a better way to get this out there than just uploading a PDF — and if uploading a PDF is the answer, then how can I make it as painless as possible?

This can come across as the designer is that jerk who always says ‘no’… That’s only because this process is not ultimately about the you, the publisher. You still win, though, because your visitors are less annoyed by your site.”

Also I would like to point out that I don’t mind PDFs at all for what I consider is their intended use. To preserve a print layout in a digital form. They are often good enough for a particular user cohort but are much more restricted in functionality than HTML, CSS, and JavaScript. Also the problems created with PDFs compound. Once you have a large amount of legacy PDFs they become locked in that format forever. As most organisations have little expertise in professional PDF production it gets costly to modify, maintain, and make accessible legacy PDFS.