Sorry but after 2 decades training pilots my experience tells me that you’re wrong. As you posted there are pilots that even transfer from helicopters and they do well in training but companies hire the individual that they feel by experience will have a better chance at completing training within the budget allowed. Money is the key factor here, it’s not only the aircraft but the type of flying as well. Generally people with heavy time under their belt also have lots of international experience and that’s another key factor for their hiring criteria. So yes, Boeing time (specially heavy Boeing) does make a better candidate on average. There are exceptions to this of course but small outfits don’t have the budget to train pilots as the majors do, so they hire based on the highest probability of success in training.