Generally, I agree. But not this part. AA's MIA hub does not exist for the purpose of connecting Texas to New York. And yet AA has a hub there anyway.
And it's a hub I'm somewhat baffled by the longevity of-- but makes sense for Caribbean/Latin America. UA has Latin America covered fairly well from Houston (which is not a great but better than MIA) and the Caribbean is...I have questions if UA could more effectively serve that from from Orlando vs the current IAH and EWR (which has a significant ex-pat population) .