I remembered that I was gate checked at CDG long time ago from HKG. They stopped several Chinese Nationals and asked them where they are going to. A lot of them were heading to Spain at that time (heard that the French police was speaking Spanish to them). When we enter France, the border police waived us through as soon as he saw our passports and boarding pass - so he knows we are definitely seeking asylum in France :P

Gate checked when arriving from IST several times. I flew TG once and was checked too.

A long time ago (20 years ago) we flew UA from HKG to SFO, and we were told to remain seated until all our passports were checked.

Don't even know if gate check is the most efficient way - if you really want to throw your passport away, there are tons of places you can dispose them before getting off the flight.