If anyone thinks that, they would be best served talking to the Joomla or Drupal (or any other popular, large-scale, user-facing, and general purpose open source project out there) and get their perspective on how that actually works out in reality.

I know we have this sense that open source software development is one big happy stone soup where everybody pitches in, but at some point, people have to make architectural and system design decisions and map out a direction in order to make any sense of those changes.

In other words, "many eyeballs" don't make all bugs shallow, they make them more noticeable. Which in Diaspora's case, is more of a problem than a benefit.