How is it possible that my flight was delayed for not having a crew?

[Retrograde]

70. On a recent international trip, 5 of my 6 flights were delayed

Flight #1 was delayed because the pilot had the mechanics checking on something (fine, I don't want a plane with me in it to fall out of the sky)
Flight #2 was delayed first to wait for passengers whose flights were delayed (this was the trans-Atlantic leg, and I was one of those passengers) and then spent an additional hour getting de-iced.
Flight #3 was delayed due to heavy fog at the destination (observation: German passengers can be just as dickish and rude as Americans)
Flight #4 was delayed because it had to wait in line for the de-icing equipment at a small airport.
Flight #5 was delayed and I forget why: it was becoming the new norm by then
Flight #6 was actually on time, but because #5 was delayed I missed it. The airline rebooked me and got me home the same day - barely.

Since a lot of the flying I do goes through Chicago I've come to expect weather-related delays. I've seen flights cancelled because the pilots didn't want to fly through the tornado approaching the destination (one frustrated passenger started screaming that it was all Dick Cheney's fault, which didn't help matters any), and was once on a plane waiting for takeoff when a small tornado came through (the airport insisted on sending people out to inspect all the runways before letting anyone more, delaying us a further couple of hours). I haven't been delayed by a volcanic eruption or earthquake yet.