Graphic designer here (you may be one as well). I release a PDF regularly, online, that a LOT of people see. It contains some vector artwork that I’ve spent a lot of time creating and that I don’t really want people to steal, for various reasons.
I make one entire side of the document into a raster image, and create my PDF for the web from that, rather than exporting the PDF from the working document that I send to the printer. It has a side benefit of reducing filesize a lot, since the vector drawings are massively complex, and it’s much easier to get a reasonable PDF filesize with good quality when exporting a single raster image.
The resolution allows people to still print it and view it online very acceptably, but it doesn’t let people steal my work. The vector stuff is super detailed and super complex, so there’s no danger of someone using Illustrator live trace or similar and getting everything that the true vector files contain.
Something like that wouldn’t stop people from OCRing the text, only from them from copy-pasting the text. But for my purposes, it works great.
Way apples and oranges. Creating versions of images that are suitable for end users but give no edge to someone who wants to steal some higher level of quality is… well, not trivial if you know what you’re doing, but easy. A web-res image is never going to show up on someone else’s printed work.
Text is another matter - it’s inherently its own complete content. Even if presented as image files, the text data can be extracted, and as you move back into live-text files of any form, it gets easier and easier to do so. I don’t know of ANY method to release text information in electronic form (or, really, any form) without the possibility of piracy by relatively unskilled individuals.