If we already understanding about price action will be not necesary to use indicator because from the historycal price we can decide which support and resistance area. I have seen many professional trader just use 1 indicator only for trading, the more important thing is knowledge about how to read price pattern.
For the short term, maybe the indicator is not really needed because you only need a candle on the chart. but for the long term
certainly indicators are very important to determine when you have to buy and sell
If trading for some chances and taking the risk in this short term opportunities, indicators are needed in order to make some good assessment,
knowing the right pattern and observed it well to make sure that you are following the graph correctly, most traders still doing and using this
factors in order to make a possible advantages.