There are technical reasons why Drupal's maintenance page exists - end-users don't care about the technical reasons behind a maintenance page. End-users come to a website to get information. To their minds, if they can't get this information immediately (from their perspective) the website is broken. Sure, the maintenance page can provide some more information and reasons why the website is unavailable. Still, a website's digital door is temporarily shut. The expectation is that the internet superhighway is available 24/7, yet in the Drupal community we are okay with a little downtime every week or so.