Stayed at the same property on two separate occasions, one time the front desk said they already have card info on file and the other time I was asked to swipe it. I had a feeling that if I didn't have the card, they could probably still charge it, but since it was in my wallet anyway I didn't push further. So definitely a YMMV situation.

Maybe the key is whether the reservation required a deposit? On the final payment page, sometimes it says credit card guarantee, sometimes it says deposit will be charged on a specific date.