User blog comment:Krishna d/The Dawn of the Infection/@comment-1701451-20091119185045

I think that Valve wanted to create a game that is fun and can be played anytime (and they did) maybe they thought putting the cause of the infection in the game may indicate some kind of plot nd they feared they'd end up with a game like every other, with a plot that gets boring and monotonous...Personally one of my favorite things about L4D is the fact it has no plot and can be played over and over again and not get boring, among oter things of course =]