Because they needed a way to get audio to the AirPods wirelessly and to work with their devices? That’s a pretty good reason to use Bluetooth.
I doubt they got together and tried to scheme a way to break Bluetooth in this one tiny little way for vendor lock in. You can use the basic AirPod features with other Bluetooth devices. It’s just these extended features that were never developed for other platforms.
HN comments lean heavily conspiratorial but I think the obvious explanation is that the devs built and tested it against iPhone and Mac targets and optimized for that. This minor discrepancy wasn’t worked around because it isn’t triggered on Apple platforms and it’s not a target for them.
Some pictures here: https://www.reddit.com/r/assholedesign/comments/b1u08k/this_...
Support is very expensive. Say what you want about Apple, but they provide absolutely stellar support, especially with the stupidly inexpensive Apple Care insurance. This is only cost effective if they can make reasonable predictions about how their devices will behave in any given scenario. Interfacing Apple hardware with non-certified (MFi, BLE, etc) third party hardware has a non-trivial risk of unpredictability high support costs, either from excessive Apple Care claims, customer support communications, or just overloading the Genius Bar.
Reducing support cost could easily explain the motivation of the entire walled garden if they are sufficiently high.
No conspiracy needed, surely it would be unilateral? It seems exactly the sort of thing Apple Computers would do to protect their ecosystem.
Truth is, no one has the full facts so any reasons as to why this was made the way it was is pure speculation. Only a fool would move to condemn or endorse what is not yet fully understood.
And what do you mean by "conspiracy"? I would be shocked to find out this was done by some lone wolf and wasn't built with broad (even if grumbly) consensus in the relevant teams. That's how corporate software is built.
But you can have an extension cord which accepts USB on one end but doesn't accept USB on the other.
So the keyboard has a superset connector so that it can go in regular USB and notched USB, because it is verified to work right when using the extension cord.
This design also means you can't plug one extension cord into another to get an even longer distance (which the keyboard wouldn't expect). Pretty clever solution.