Sometimes it is necessary to add a comma to make a sentence clear.
Unclear: In the kitchen cupboards were empty.
(Make it clear that the phrase is “in the kitchen,” not “in the kitchen cupboards.”)
Clear: In the kitchen, cupboards were empty.
Unclear: The room was full of crying babies and mothers.
(Were the mothers crying, too?)
Clear: The room was full of crying babies, and mothers.
Clear: The room was full of mothers and crying babies.