But they were (slowly) checking the passports of even travellers to EU (non-Schengen) destinations, with just two immigration staff on duty and hundreds of irate people in the queue. And the fact remains that the UK does not have a passport control for any departing passengers, regardless of destination -- only the airline checks them, and if you have an e-ticket, only at the gate. The same is true in the US. So why do the French feel the need to check them?
Incidentally, the CDG security checks were being handled efficiently and fast -- it was just the unnecessary passport control that was bottlenecked.