This is something that keeps me worried at night. Unlike other historical artefacts like pottery, vellum writing, or stone tablets, information on the Internet can just blink into nonexistence when the server hosting it goes offline. This makes it difficult for future anthropologists who want to study our history and document the different Internet epochs. For my part, I always try to send any news article I see to an archival site (like archive.ph) to help collectively preserve our present so it can still be seen by others in the future.
Inability to edit or delete anything also fundamentally has a lot of problems on its own. Accidentally post a picture with a piece of mail in the background and catch it a second after sending? Too late, anyone who looks now has your home address. Child shares too much online and parent wants to undo that? No can do, it’s there forever now. Post a link and later learn it was misinformation and want to take it down? Sucks to be you, or anyone else that sees it.
There’s always a risk of that when posting anything online, but that doesn’t mean systems should be designed to lean into that by default.