Comment by sumuyuda
I think the reason is Apple wants to make it hard to turn off Wifi, so your device is part of their Find My network and will support other Wifi based data collection they do.
The buttons doesn’t actually turn off Wifi or Bluetooth, they disconnect from the current network/device. This is a huge dark pattern.
Sure, but they could still provide a solo toggle for Wifi, which continues to do the disconnect instead of disable behavior.