Furthermore, I'd imagine that the host might be required to retain those records for law enforcement purposes (imagine if someone made death threats, etc and law enforcement requested those records for an investigation).
This is based on my personal layman's understanding. I am NOT a lawyer. I am NOT your lawyer. If you need legal advice consult a competent lawyer in your jurisdiction.
It is to prevent people going to their Bank, where they have a credit card or a consumer loan, or a mortgage, and say "can I please be forgotten/be wiped from your systems - oh and the loan too!".