They are not perfectionists. They have many small groups or "cabals" where everyone's input is heard frequently and features are cut when the look like it will

They are not perfectionists. They have many small groups or "cabals" where everyone's input is heard frequently and features are cut when the look like it will not increase the fun of the game. Couple that with the fact that they have some serious talent on board and they know when it is beneficial to outsource(physics engine for HL2:Source) and you have a pretty good foundation.