Because supporting an aircraft on a controller is not free. There's much more to this than just protocol.
DJI has to make a decision if the support costs over the life of the drone and RC make sense, and I can see why they would judge the number...
At the bottom of your page on the DJI web site, change your country / language to (Canada / English) and you’ll be able to see and download all the Neo 2 stuff, Mini 5 Pro, etc. You can also do this through your VPN, but it’s super easy to do...
I'm highly annoyed that the RC2 does not support Quicktransfer downloading of full-resolution media from the drone to an inserted SD card.
Or does it? If so, someone tell me how :D