for channel modes 1-3 , yes you have only the basic channel … where things change is for channel mode 4, at this point you have the basic channel and then voices channels.
mode 4, as i understand it, is a bit like the proposed MPE standard… in fact, some are saying MPE is not even necessary because mode 4 covers most requirements.
so yeah, in mode 4 , i would totally expect a cc123 on the basic channel to kill all the notes!
anyway, forgetting notes off , as perhaps a bad/confusing example, look at some of the others:
CC122 turns off local control… i.e. you keyboard is detached from the synth engine, nothing to do with midi channel.
CC123-127, this combination can affect how channels are handled (e.g. mode 4) means that sending this on the basic channel, affects how the other channels behave.
so , getting back to the pyramid and original question…
the point is these ‘cc’ are more about how the midi protocol/synth works , rather than being a ‘synth parameter’, so it doesn’t really make much sense to modulate them… as the pyramid might be using them anyway as part of the ‘UI’ (e.g. it sends all-notes-off (cc123), and all-sound-off(cc120) when you press stop)