Bungie had only marginal experience supporting online persistence in the style of an MMO. Building the new systems from nothing and building them in such a way

Bungie had only marginal experience supporting online persistence in the style of an MMO. Building the new systems from nothing and building them in such a way that they could scale required tremendous investment. Activision/Blizzard operates World of Warcraft, the largest and most successful game of it's type. And they had the resources to allow Bungie to build something much larger than anything they had ever built before.