It was never a publicly stated policy and, anecdotally, they seem to have stopped doing it on newer phones. But one person escalated to a manager (because the first-level support staff didn't understand the difference between carrier unlocking and bootloader unlocking), and the manager stated that it was their policy.

And, yeah, I agree that it's probably the worst of all situations. If I'd have known that a google repair would cut the phone's lifespan in half, I'd have just done the repair myself, or else hired someone local to do it.

I doubt it is intentional. I heard they'll fix it if you contact them