It's a felony to tweak your Wifi beyond specs, it causes issues and regulatory bodies react, OpenWRT and DD-WRT could've saved them selves the trouble by developing a mechanism to respect local regulation own their own.

The Linux kernel has such mechanisms and they're not trivial to bypass. You'd as a user have to go out of your way to do so, and the devs are not in favour of users doing this. (source: I had to do so to workaround a card that was configured for completely the wrong regulatory domain).