I overheard a couple of gate agents at MKE talking about how they can't hold flights like they use to. I have to say that a couple of Frontier flights that I was on we waited in DEN for connecting flights but no more than 10 minutes each time. I didn't see any new people board the aircraft so I assume they missed their connection. DEN is a much larger hub and they can accommodate people that miss their connections easily. MKE is a different story and I understand the gate agent's frustration there. I would think that YX could have rebooked your friend on a Delta flight to RSW.