A lot of people have taken jobs with poor terms and in less than ideal locations because they were the only jobs available. Those advocating seniority lists tend to be those who fortune has heavily favoured with their CV crossing the right desk at the right time - getting the plum jobs has much more to do with chance and contacts than ability and character. So, should those who have put up with awful jobs be further punished by being frozen out unless they start from scratch again just because they didn't happen to complete their training when a legacy carrier was recruiting?
Odd how those advocating the seniority lists accuse others of selfishness; seniority allows a precious few to cherry pick type, base, routes, leave and the best pay at the expense of their colleagues in the same airline and to freeze others' careers in inferior jobs. That's hardly a generous spirit is it? A little hypocritical to accuse others of selfishness, no?