ASUS did this on the latest firmware on some of their Routers.
This was the cause of no end complaints on various forums but ASUS did not relent.
It was simply to ensure that the modems if imported back into the US did not break FCC Regs.
The fact it did NOT strictly comply with Regs outside the US did not matter to them at all.
i.e. Other countires allowed a bigger range of channels.
(They had previously been pulled up, via a competitors complaint, when a router tested exceeded that regs and got better results.
I believe it exceeded the allowed power output or something similar)
For ASUS as long as you are within the USA FCC Regs that is all that matters.
The FCC appear to trump everyone elses rules.
They argue that although restricted they do comply with the rules outside of the US as well.
True but limiting when there are more channels that you
could use to avoid conflict of channels.