Are baggage charges to blame?
I traveled with KLM from Dublin to Lyon via Amsterdam. The Dublin to Amsterdam sector was Aer Lingus.
To cut a long storey short, because there wasn't enough space in the overhead bins the flight was delayed which in turn meant my connecting flight was missed and I overnighted in AMS.
Are overhead bins designed to offer sufficient room if each passenger arrives taking their correct quota of baggage, coats etc? In my case I guess they didn't and the overflow presumably lead to items having to go in the hold with the inevitable delay and missed slot.