PDF is not very fine. Copy-paste from PDF very often results in complete rubbish, even when it is not deliberately prevented (which the format allows, and then you have to do OCR).
People purposefully disallowing copy-paste isn't a problem with PDF: in other formats they would have embedded a picture, at least with PDF you get the other advantages of proper text: infinite zoom and great compression. Sadly there's also a lot of PDFs that are little more than a picture collection that looks like text, but that's hardly the file format's fault.
It really is a problem with PDF that it's too easy to get a file where copy and paste yields a different result than what's displayed. But this varies widely with the software used for creating the file (e.g. latex ligatures never work in copy-paste)
When the PDF is a picture collection that looks like text that's when PDF is being used correctly, because that's when something was scanned out of paper and put on a paper-like format for computers, PDF.
When people write text and data and tables on the computer then put it on a paper-like format to share that's when the problem happens.
Have you ever actually tried to parse PDF with software? It's a sheer nightmare. PDF often gets produced from text processors that have very rich format information. PDF strips it all out and then you somehow have to recreate it.
It really is a problem with PDF that it's too easy to get a file where copy and paste yields a different result than what's displayed. But this varies widely with the software used for creating the file (e.g. latex ligatures never work in copy-paste)