This will be brief.
Inbox zero is a valuable thing to maintain. Roughly promoted around the web as having an empty inbox.
An email inbox collects a few things:
- junk
- automatic mail sent to you
- personal mail sent to you
- work sent to you
- (maybe - work you send to yourself because that's the best way to store information for now)
- Old as all hell (or other friendly name)
- 2014
- 2015
- 2016
He also hasn't mentioned that you should exercise regularly, eat vegetables, invest in index funds, and not get addicted to heroin. Why should there be anything about passwords in an article advising people on how to get accumulated cruft out of their email inboxes?