Chains hit the chainstay all the time, much more ATB than road, but both.
Every bump, hole or even a low speed roll off a curb result in chain slap on
the stay. At best it gets greasy, after time the chrome or paint chip off.
Some thing needs to be there. Another place where protectors are needed
is on road bikes on the sides of the head tube. Notice where the shifter cables go and if they hit the head tube when the fr wheel is turned side to side, then a rub mark will appear in 6mo or a year. A bit of tape there is prudent.
Steve