<i>What&#x27;s the risk of using plaintext passwords if we assume every user is employing long, random, unique passwords?</i><p>This assumption is known to be false.  We should not design systems around this assumption.  If we do, popping a random startup will give up Gmail accounts, <i>by the thousands to tens of thousands</i>, and since we&#x27;ve settled on email accounts as The One Ring To Your Identity that imperils their brokerages, domain registrars, employers, World of Warcraft characters, physical safety, privacy, cat photos, etc.