You could sit confortably to eat on a bed. But you can't do it in the bed. And whatever is your posture to eat, it is one you'll take to chill in a bed. So what the point? Why put crumbs, sticky stuff and beverage to a bed that will to be confortable ?
I was going to say "It is late where I am" but I was fully awake when I wrote this. I'll keep it as it is.