PDF gives you all the tools to make sure that doesn't happen. No one prevents you from shooting yourself in the foot by writing a bad PDF that doesn't adhere to common good practices. For example it is technically possible to make a PDF with text without embedding fonts. Doing that is a bad idea.
By your argument, any programming language, no much how safe it purports to be, fails because they allow you to write bugs.
By your argument, any programming language, no much how safe it purports to be, fails because they allow you to write bugs.