Sure, there's a variety of official and quasi-officials resources that should be treated as public record and preserved. And arguably, there are things that rise to the level of a cultural phenomenon and where the benefit of keeping receipts outweighs the jerk factor of never asking for permission and not respecting the wishes of private individuals.
But if it's some family blog from 30 years ago that's been deliberately taken down and lives on archive.org unbeknownst to the original owner? Do we have a right to that? To what end, other than "well, future historians may need it"? A historian won't look at it. A person trying to doxx you or shame you will.