I agree with you, many more factors then the 10 DMA get involved in the decisions to buy or sell. Using one chart or many charts to show that this parameter should be leading is like proving that all odd numbers are primary numbers, 1 is, 3 is, 5, is, 7, is, 9 is (oops, statistical error), 11, is 13 is and so on... (g).
Look at your own chart, on 3/22, the 10 dma would have taken you out of QCOM(g). Probably at $62.30 or so, since you must wait till the EOD to determine what to do. Well, a week later you would have to buy it back at $65.61 or miss the run to $69. Then, after selling at $64/5 on April 15th ( a loss or even, your 10DMA does not suggest a selling point but the breach of the 10DMA on a red candle, if I got the trading 101 correctly) breach of 10 DMA on red candle), you'll be forced to buy back a week later on 4/22 (above 10DMA on a green candle) around $68/69 just to be forced to sell again on April 28 around $64 (another loss). Similar whipsaw pattern would have taken you down few bucks 3/5 (buy at just under $65) sell on 3/11 under $62. I think the 10 DMA technique is a useful tool, like many others, but as you said, it must be used in conjunction with other tools, including a view of the general market (which, unfortunately, can often be wrong...).