Paper is in fact pretty durable. A lot of History came through millennial papers.

I’m not saying that computers manuals will for sure stand the test of time for a the thousand years to come, but as long as they are protected from fire, they are probably a more reliable storage than a digital scan which will need humans to backup them regularly if they want to survive their physical media.

Sure digital backups, especially of PDF files, are easy and cheap, but they require an active human effort to keep the system alive.

Obviously I'm describing the ideal situation, and sometimes practical realities mean we have to compromise on the ideal.

Still, as much as is practical, we should try to avoid throwing physical documents out even if we know they have been scanned.