In raging over this practise, there's an unstated assumption: That the alternative is selling the full, unlocked chip at the consumer price point.

This is very unlikely to be the case. Like first class on a flight, the pricing of the high end is likely subsidising the lower end. Of course, there's still a profit margin on the low end offering, just not enough that it can stand on its own.

So the alternative to this practise is a cheaper high-end chip for everyone, it's more expensive (or same price) high-end chips, which means the low end of the market get's priced out and have to make do with last years model.