Apparently in Flèche it was warm and sunny early on so everyone shed layers, then a storm blew in and temps dropped to near freezing with rain. A lot of guys tried to just keep going and/or were not able to get to cars to get jackets, plus the circuit went right by the team busses (temping!) so the race finished with like 40 riders. I think 3-4 teams had zero finishers.
My fave stat is that the only team where everyone finished was the Norwegians from Uno-X. Presumably this was just a normal day at the office for them.