Obviously almost everyone has a device to receive BLE whereas zigbee is a bit more specialist. I've been playing with some arduino hardware that supports zigbe

Obviously almost everyone has a device to receive BLE whereas zigbee is a bit more specialist. I've been playing with some arduino hardware that supports zigbee as well as BLE, and BLE is trivially easy to get working where the zigbee stack is much more complicated and much less documentation. So I would guess that plays a part too.