[meowster]

Notarization just proves it was you who signed something, it has nothing to do with the contents of the document.

Unfortunately a lot of people think notarization gives some kind of legitimacy to a document, or likely in this case, it's probably not the hassle of getting it notarized, but used as a scare tactic to prevent some people from committing insurance fraud by listing inflated or made-up items (people might conflate it with perjury).

[s1artibartfast]

It proves not just who, but when. This can be pretty relevant in a number of situations.