Ok, you are right, that gate 1 2 3 4 would create an error. But route 1 2 3 4 and gate 4 would have the same effect. For example live.step
can send output to different channels using route or using gate!
'list' is an undocumented message. It seems to put the second (and only numerical) element into right inlet. And, since in [gate]'s right inlet is hot, first this value is outputted and then gate changes its destination outlet.
btw @more_experienced: has that feature any application?