It's a technological and a physical issue. We just can't store every bit of information plus a picture of everyone's cat. We can't guarantee that no information ever gets lost. We've also not really stored and archived every shopping list, advertising, pamphlet, silly poem, ugly drawing etc. since the time of the printing press and that's okay.

It might be a good idea to store and archive some written material as time passes but we want to be a bit picky about what we store. That said, I wouldn't mind to find more shopping lists and less posh documents in museums.