Hardware that wouldn't exist without the high margins generated by their vertical integration.

If they posted the bootloader keys to Twitter right now it wouldn't lose them any money. Nobody is going to stop buying their shit because of that, but rather they might start selling more because now they can use the hardware for applications that would have been previously impossible.

To put it differently, Skyrim would have died as a game within a few months of release if it didn't support mods, but instead they didn't try to restrict them and made a horrifying quantity of money as a result.

That may be true now, but it doesn't debunk the point that the hardware that is now so desirable exists solely because of their vertical integration.