Quote from baro-san:
PA is like speaking the language, while using indicators is like using a conversation guide in that language. So the performance you get when using PA vs. indicators, is the same when you talk to a foreigner and you learned his language vs. when you're using a conversation guide.
I have a different interpretation on indicators.
Indicators are like the information on the dashboard of your car.
Speedometer is an indicator. It indicates the speed you are traveling.
You could drive without a speedometer. You could get a feel for how fast you are driving by seeing how fast you are passing your surroundings, feeling the winding that is blowing into your car, sticking your hand outside and feeling the wind, etc.
I would prefer to drive with a speedometer than without one.
I think indicators help.