WTF is it that employers think they can get out of the last 7 years of addresses? That's private information, absolutely none of their business.

It helps catch attempted identity theft. Lots of people who are not eligible for employment steal the identities of those who are. But they will have to make up any data they don’t know, or that is inapplicable because the true holder of that identity died a while ago.

It's used for background checks to identify relevant criminal records, debt records, etc.