Probably because SystemD network management is harder to use on a headless install. With a Raspberry Pi you just need to edit a couple of lines in the boot.conf to have it connect to WiFi on boot.

You can deploy one without ever plugging in a keyboard or monitor.

How do you edit boot.conf without a keyboard or monitor?

Mount the sd card elsewhere, the boot partition is FAT formatted and can be edited on most OSes.

you pre-configure the boot.conf and other settings on the same system you use to write the raspbian image onto the microSD card, before you put it in the pi. if you get the config right you should be able to boot a pi headless and ssh to it over your 802.11n/ac/ax network immediately after the first time it powers up.

This question is so apt that it gave me a chuckle. I've done it before, but I had to think about that one for a second. You have to edit the file while the SD card is plugged into a separate computer.

it's on a FAT partition, you can edit it by plugging the sd card into something else

Well that's stock on both Debian and Ubuntu still, right? It's more of a question why they haven't replaced it either.

Been a while since I've used Debian but I'm sure Debian is already using NetworkManager. This means the Raspberry OS has actually removed NetworkManager from its Debian base and put in something else. I agree with the OP this shouldn't happen. For my Raspberry Pi, I ended up switching out the Raspberry Pi OS' default networking manager thingy in preference for NetworkManager so I could share wireless networking configuration among my devices. It also helps with troubleshooting as well since I can just use the same commands I use on other Linux machines even those running other distros.

It’s not.