plenty of stuff (like credit card info for instance) should absolutely never be auto-completed. The browser storing that sorta stuff to disk is stupid and completely avoidable.
Already caught chrome doing this to my Social Security Number before i disabled the functionality entirely. The idea of Chrome automatically auto filling any form it sees labeled "SSN" on any site dosen't inspire confidence.
One CRM webapp I worked on took our frontenders several attempts at different hacks to get Chrome to stop treating the SSN-equiv field as a credit card autofill.