For most of my trading life, I have used some form TA, which also includes Price action in form of bar charts, Candles and P&F. Whether I day-trade futures and or stocks, except for the personality that each display, all offer similar patterns. I can trade off just using the DOME, but I regard this as pattern trading, a form of TA. I believe 99.9% of traders, whether long, swing or day trading regarding Commodities use some form of TA, since most of the Fundamentals are often late and already factored into Price. The only signal that I have found to be consistent as far as using just fundamentals in Commodities, is fading the original price action after a report comes out, and that can also be considered to be TA as well, as I look at intraday chart.
Even in stocks more so now than when I first started in 1981, one can still use just fundamentals for inventing long term, but I know of no one personality that day trades away from the floor just using fundamentals and makes consistent profits year after year. Of course one can wait for earnings to come out and see how reacts to that by either going with trend or fading it.
It is funny, when I was much younger, I actually thought a new indicator could do something different than others, you play the game long enough, you find all indicators to do about the same wiggles, it is how you interpret the wiggles is the gravy. For fun, sometimes I do a "Woodie" and get rid of the chart to see how close I can get to drawing a chart from the indicators I use, am pretty close most of the time. So whether you trade off just charts or add indicators, just comes down to studying them so well, remembering what to do as your experience grows.
Most traders are "secretive" for several reasons, yes, some methods can be over traded and stop working, some traders spend 10,000 hours plus developing their methods-why hand out the golden goose for free, another is some methods are so difficult to learn you would never understand it anyway.
There are a number of "edges" in trading, and so many people lose and they say don't why, when actually successful trading is the absense of dumb mistakes. Trading real money when one does not have a well backtested method, lack of patience to wait for signal, having a set goal, have 1-2 entry signals and 30 money management rules. I believe if most losing traders could rid themselves of 1.5 bad trades a day, they would have a profitable week. too many concentrate on making losing trades into either winners or breakeven trades. By studying why the winning trades were winners, this can get rid of more bad trades.