Quote from Fractal:
I think one of the sticking points with TA practicioners is that they do not rely on a small set of variables in a vacuum. You do not buy just because of an MA cross, but in certain conditions (futures approaching yesterday's highs, lack of bearish news and weak earnings for the day, Fed paused three days ago, similar company in the sector making new highs), an MA cross or a high and tight penant can provide a good enough picture of market sentiment.
TA -- or charts, really, applied in a comprehensive manner, cannot be well analyzed by running a few variables through 10 years of data. Chart patterns by themselves cannot and should not be divorced from larger market/sector conditions, which often fluctuate so much and then suddenly all snap into focus in one instant to provide a signal.
The argument to me seems to be more between people who want everything to line up exactly in black and white, and demand that TA serve their needs, and those who simply use TA as a measuring tool -- primary, secondary or otherwise.