From my opinion: There is multiple ways to answer why we are not using any type of indicator? the simplest answer is to be able to depend rely on the price only to justify our entry,exit and risk. in Bob Volman methods we are taught to use false high/low or False break to evaluate how we can use this type of info to our advantage with bollinger band basically you are focused in price high and lows which can send a false signal to enter or to exit a trade.
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