I've noticed that the label "Wireless On/Off" on at least the TP-Link Archer C7 and TP-Link TL-WDR4300 and the position of the switch are inconsistent, at least in my mind. When the switch is to the right (On/OFF), the RF is enabled, when to the left (ON/Off), disabled.
If you've got an ar71xx device other than these two, is yours "backwards" as well?
(Yes, I've already considered that a change could puzzle many users if they flash it and don't read the "release notes")
On the WDR3500, which is very similar to the 4300, it runs through /etc/rc.button/rfkill. This script incorrectly assumes that the switch is a button instead of a level. Each time it is "released", the wifi is toggled between enabled and disabled.
The wifi driver itself is not directly involved. It is done by changing the UCI configuration to disabled.
I generally chmod -x the script so the switch has no effect.