There are a few reasons for this. First and foremost, Infernity has a tiny player base; not many people are using the deck anymore. Additionally, the skill levels of what few players we have is... sub par to say the least. If you've seen the quality of players using this deck, or if you've read the hideous Infernity thread on Pojo, you will learn quickly how incompetent many Infernity users are.
Forgive me for that short rant. Moving on, I don't think Infernity players were meta prepared. In retrospect, should I have gone to such an event, I would have made some major changes to the main deck. With continuous cards running rampant in the current meta, I would like to have maxed out on MST and mained a Dust Tornado or two. The most likely candidate for being dropped is either my beloved Archfiend's Roar, the Book of Moon which is becoming more ineffective every day, Trap Stun or Infernity Break. MST and DT would have made life so much easier for Infernity players.
Those two main deck choices would have quite happily dealt with GKs and Dragunity, and would have eased the burden of the Samurai match up. Only testing will tell.