It's important for people writing papers and such who need to cite material.

I wonder if there's some way to use the TLS certificate to get a cryptographically-signed copy of a webpage with timestamp that someone could later validate as having been downloaded on that date. I don't know if existing TLS libraries are capable of that. Like, Web browser menu option "Store cryptographically-signed webpage". Absent a later certificate compromise, I'd think that that'd at least provide people a way to credibly say "this is really what was on that webpage on August 15th, 2026". Like, you'd have to save a copy of the TLS session and then have libraries that could read and validate an already-generated session. The timestamp is already embedded in the session.

Some protocols, like OTR, are designed to specifically not allow that, but AFAIK, TLS could.

EDIT: Well, technically the timestamp is gonna be during the handshake, not tied to the HTTP request internal to the TLS session. It might be possible to game that by establishing a TLS session, holding it open without activity, and issuing a request much later. I'd think that that'd potentially be disallowed by Web servers one way or another, since otherwise you could probably do a denial-of-service attack by holding open a lot of sessions for a long time.

EDIT2: Oh, wait, no, shouldn't be an issue, because the HTTP Date response header is gonna have a timestamp tied to the response.