What you say is perfectly reasonable regarding popular content like movies and novels. Even computer games. However, of personal data like photos and writings, much will be lost. People (or their children or their grandchildren, etc) won't bother to convert everything to new formats and they won't bother to copy all files when they upgrade hardware. Alternatively, they could upload their data to a third party who, for an annual fee, would store and continually upgrade the files to newer formats. However, companies go bust. Conversion software is buggy. Passwords get lost or not handed on. Descendants go through financial bad patches. A single break in the chain is enough to destroy information.
Thus to preserve data you really do have mingle it with hardware and mass reproduce the whole thing. In the biological analogy, genes are the data, DNA is the medium and the rest of the seed is the 'reader'. Making hundreds or thousands of copies ensures against total loss.