Hold a sec, when I said you won't get asked for the card, I just meant for redemption bookings.

When I make ex-China bookings and pay with an Amex over the phone (because the online system only accepts Unionpay, Visa, or Mastercard), I have been asked for my card 100% of the time.

If you are making a booking for someone else, you can sent a copy of your passport info page with a copy of both front and back of your credit card to the airline and that's usually enough to clear the need to present a card upon check-in. And I have found they will only ask for the card if your 'Manage My Booking' page lists such requirement.