Forgive me for taking a cynical view of all of this, but it does rather smack of putting as many flights on sale as you can to generate forward ticket sales cashflow.
They're prioritising routes where demand can be expected to resurge quickly once the public is allowed to travel freely again. A trip to Orlando is discretionary in most instances - it can be left for another year or so if money is tight or if some family members harbour residual concerns about C-19. But if your extended family lives in Pakistan or India and you haven't been able to go and see them for ages ... well, that decision is a quite different one. Volume bookings will come in once travellers are permitted to cross borders without quarantine once again.