These rules actually aren't limited to the domain registrar or the ccTLD regulatory body, but rather imposed globally by ICANN which manages all domains.
So, it is important to update your information if they are no longer current. Penalties include a fine for contact details that aren't updated.
These rules are there to prohibit people from holding a domain indefinitely (or until they expire) without a way to contact them. In fact, you can report a bad whois lookup to the registrar, and they are actually required by ICANN to update this.
Also note that this also prohibits the use of fake information. If they find out that they use fake info, then your domain gets taken away from you.