Dileep

First, let me tell you, there is no perfect strategy in stock markets.
Now coming to technical analysis, it is nothing but finding patterns in charts.
Now why they fail is:
In trading, anything that is easier to earn attracts fast attention, and the gains were evaporated quickly within seconds because of the functioning of algos at higher speeds.
The same information is available for every trader from novice to Market Makers. What markets know novice doesn't know is the limitations of an indicator and strategies; these people play at the weak points and trap all the average traders after all Your loss is his gain.
These failed indicators continue to stay on signal side for much longer than necessary trapping all average traders.
An experienced trader knows the flaws of these systems and won't trade.
Finally, remember Technical Indicators result in price action not the other way around, so there is a whole different level trading rather than depending on signals.