That’s part of the reason US based airlines don’t fly to most gulf region airports anymore. 1) they could essentially justify a lightly loaded economy section

That’s part of the reason US based airlines don’t fly to most gulf region airports anymore. 1) they could essentially justify a lightly loaded economy section due to Business / First passengers (I’ve done several cheap mileage runs before where I had multiple rows to myself in economy). When those $$$$ passengers switched to the nicer Emirates/Etihad/etc flights, they lost that marginal advantage. 2) on top of #1, another major factor is that Etihad/Emirates/etc are heavily subsidized by their national governments. Due to this, the slot fees were much cheaper for them than US based airlines further reducing any money to be made on those segments by US based airlines. The end result of the above is that now you have to use an alliance partner + connection to get from US to the Middle East (or fly a MENA based airline) where as before you could choose from dozens of directs.