WHY ONLY FIXTURES AND NOT ALSO SELECTABLE CHANNELS?

[Giancarlo]

HI TO ALL!
PLEASE WHY ONLY FIXTURES AND NOT ALSO SELECTABLE CHANNELS? I MEAN MAPPING A FIXTURE COULD BE USEFULL FOR CMY OR OTHER STUFF.
THIS WOLD BE A GREAT NICE AND POWERFULL FEATURE TO HAVE IN OYX!
THANK YOU.