I don't think that's true really. Yes most of the data recorded today will be lost but there is just so much being recorded that what remains is still much more than what we have of previous centuries. What we have of the 4th century is limited to a subset of what people specifically chose to write down. What will remain of this century includes that plus much more incidental information like the backdrop of a selfie that could turn out much more interesting to future historians than what you think is important now.