The wifi thing is slightly understandable because FCC requires you to limit your radiated emissions, and when you do the certification you have to control the entire configuration to pass the testing, which means that your radio is paired with your antenna cable and antenna in the body of the device. Allowing people to replace the radio without a paired antenna cable and antenna could cause radiated emissions to fall outside of the spectrum allowed by the FCC. It's dumb in practice but at least somewhat understandable in principle.
And not just stop you or refuse to activate the card, but to intentionally cause the hardware I purchased to irreparably malfunction as long as I attempt to use something you didn't sell me.
Of course, I can use a USB wifi card, no problem. Just the convenient PCI card inside the system that is specifically designed to enable a wide variety of functions aside from wifi that is locked in the BIOS just in case I wanted to use a 3rd party card of a specification that you don't happen to sell.
Lenovo did that to reduce their customer's ability to buy PC expansion devices from other manufacturers, in hopes of making more aftermarket sales in the future.
It used to be very common across all OEMs, at least in the consumer space. I remember having to flash a modded BIOS on my 2012 HP laptop so it would boot with a WiFi + BT card. Back in those days it was uncommon for a laptop to have BT.
