It's useful for <input type=password ...> fields that aren't _actually_ passwords. For instance if a UI wants to hide some secret value and then have a click-to-reveal button. autocomplete=off makes sense in these cases because otherwise the browser tries to show worthless autocomplete dropdowns and if there's any form on the page then submitting it will also prompt you to save it in the autocomplete database. Which is also annoying (and worthless).