> Many people believe PDF to be “impossible to edit,” but beware: minor edits in PDFs, such as swapping figures on an invoice, are trivial — therefore you need other technologies, such as digital signatures, to verify that your PDFs have not been tampered with.
That's not really the point that it can't be edited, the value to me is that the sender has confidence that it will look the same to the receiver as the sender.
Different PDF reader software, and even sometimes the same reader software installed in different environments, can render PDFs, especially those containing any text differently.
If you want confidence that it will appear the same, pure image formats are a safer bet.
If I send you a PDF the point is that I don't want you to edit it. Otherwise I would have sent a docx file. An 'editable PDF' may as well get lumped in to the OpenDocument standard. It is already universally editable and I'm sure it has support for adding application-specific metadata.
Having a PDF editor isn't some violation of sacred principles; but making changes to the standard to make it easy to edit is not improving the situation. I want to send a format that is hard to edit.