If I have multiple DECO M5 devices all connected to the main hub through ethernet, why do they have to transmit in the same 2.4GHz channel, same 5.0GHz channel? The backhaul is ethernet already.

Why not have them all transmit in different channels to lessen interference?
example: DECO#1 use Channel 1, DECO#2 use Channel 6 and DECO#3 use Channel 11.

This way, I can have 3 phones, computers, TV connect to each of these DECO and each have clean channels.

I know the M9 uses dual 5.0GHz channel to distribute bandwidth, but why not just use different channels for each deco?