The only reason you would want to do this is if you use the same password for multiple things. You may have signed up with some website a year ago, used it onc

The only reason you would want to do this is if you use the same password for multiple things. You may have signed up with some website a year ago, used it once and then forgot all about it. If they get compromised you might not even know it. If you change your passwords often then you don't need to worry about this as much.