ravenstine parent
I can see people wanting that, but then I'd have to wonder why they are using PDFs for that purpose and not something like Google Docs.
Think construction plans, PowerPoint presentations, contracts - there are many documents that don't fit the classical Word document model.
But why would one expect a browser to support that feature for PDFs?
You wouldn't, and it doesn't. But webapps and websites can usefully do it.