Originally posted here by MsMittens
That means altering the document potentially that is being distributed, and the integrity of the document.
Yes it does. But what's the problem with that? I mean, it's impossible to distribute a PDF and then be sure it's integrity is kept. If someone really wants to break the integrity, they can just create a new similar document. Or use some hacker-tool on the document to alter it.

And, if you want to distribute a document which integrity is secured, PDF alone isn't the way to go. To be certain you would have to use some cheksum that would be available to the reader off your website. The reader would have to know about this of course. Better would be to use PKI to provide easy checking of the integrity.

By disabling copy/alter from PDFs you're not really gaining control over your document, but you're decreasing the usability for the reader.

Adobe provides pdf to text options, particularly for those who are disabled.
Says in the faq it won't work if copy/alter is disabled.

If you really want the document seperate, email the owner of the document and ask them.
That's a lot of hassle just to make use of a document. Usability is decreased.