Personally, I appreciate the data point and am surprised that you were shot down. I’m not saying it’s worth a complaint and attempt at compensation but it’s interesting to me. I fly every two weeks and I hear the request to gate check carryons more often than not. I assumed it was a Delta policy and that the agent wasn’t really basing their announcement on equipment or load factors given that most flights are full these days anyway.
My wife and kids travel without me 3-4 times each year (usually on my miles) and as a group of no status flyers, I always suggest she gate check bags that she doesn’t want to pay for and/or can’t easily carry through a connection. She’s never been denied but I also never thought it was a possibility. Now I know.