They're glossing over over this a bit. Many sites use the last 4 digits of your cc number as validation so the last 2 digits + email + phone suffix setup is val

They're glossing over over this a bit. Many sites use the last 4 digits of your cc number as validation so the last 2 digits + email + phone suffix setup is valuable information and is definitely an addition to any cc database for liveliness of credit cards or accounts to go after on steam.