I generally agree, but on the other hand I think the situation here presents a clear case where you could draw the line - if your airline is canceling at a rate

I generally agree, but on the other hand I think the situation here presents a clear case where you could draw the line - if your airline is canceling at a rate that's, let's say, double the national average, you no longer get to claim weather. It's difficult to punish the kind of individual cases you're describing, but from a game theory perspective that just means that in situations like today's, you bring down the hammer in incredibly punitive fashion in order to make a single systemwide failure like this so costly that it's a no-brainer to upgrade software and keep slack in the system (particularly at high-traffic, high-importance times like the holidays).