But, WYSIWYG on a 2D screen is just an inherently leaky UX abstraction when dealing with 2.5D content, e.g. layers.
The best way to redact a PDF is with a printer, a sharpie marker, and a scanner.
PDF documents do not reflow.
Definitely doable but hardly straight forward.
PDFs, inheriting from PostScript, do have the concept of fonts and text strings, which can be edited. They're not just a soup of vector shapes.
Why SHOULD someone using a PDF reader software intuitively understand that placing a black rectangle over a document and saving it doesn't prevent someone from seeing that document?! Why the fuck does anyone doing a job need to learn a set of unique and non-generalizing mental models just to redact a document!
Imagine if paper had unexpected failure modes!
The problem is not professionals trying to do their damn job. The problem is US. The Programmers. Who consistently make garbage systems using garbage leaky abstractions and absurd assumptions and ignoring decades of user interface research because google released a new UI library written by programmers who haven't interacted with non-programmers in a decade.
Why are WE still doing this?
It does. If you scribble out what you would want redacted in black ink until it's no longer legible, it's not actually properly redacted for just about the same reasons the PDF wouldn't be