To be fair, using varnish and proper cache modules with drupal, you can make drupal very immune to this sort of traffic.
Core Drupal caching can handle a lot (my blog has handled the top spot in HN a couple times with only that without issue), and adding Varnish alone can scale it to huge traffic levels. The GP comment is just FUD.
What I don't understand is why people don't get ready to take the hit; use a cached static version, use varnish, get more instances; just don't let it go down.