No, they do not. Maybe an important person's password hash gets leaked and they want to extract the password to check other sites for reuse to get into other sy

No, they do not. Maybe an important person's password hash gets leaked and they want to extract the password to check other sites for reuse to get into other systems. Now you say reuse is dumb, and I agree, yet a lot of people do it because they're lazy. This is just an additional stepping stone to make a malicious hacker's life harder.