I would also add that .pdfs are often not meant to be transformed. They are the digital equivalent of a book, which no one complains about not being able to edit. If you wanted to have a document you could edit you don't use .pdf, but something else before you convert export it as an .pdf. The same is true about images. No one complains about .jpg not being editable, as any sane person would use a photoshop or similar file and only export the final product.