It's not "only" about the TA being used...it's equally about the trader using the TA within a trading plan that consists of other variables just as equally important (e.g. risk management, position size management, trade environment, trade experience and so on).
That's what trading is part art, part psychology, part science...assuming you're not an automated trader.
Those that "only" concentrate on the TA as if it those other critically important variables do not have any merit...they will be doom in applying TA. In contrast, those succeeding in using TA...they're using other important variables in their trading plan with the TA.
Simply, TA is just a tool. Therefore, I would argue that the trader is more important than the TA because the trader is the one that needs to put all the pieces (the above mentioned variables) together into functional team (trading plan).
wrbtrader