Can if you like. Stan Weinstein uses the 150dma as do some others. Brian Shannon who trades Stocks says trading Long only when the 5 MA is trending up or when above it has saved his arse countless times. I've never looked into it, but you probably know.
Lets say you wish to create buy and sell signal trading rules and you want to use ma's. The first issue to overcome, which time period to use. You can scale from 5 all the way to 250 or beyond. Because there is no accuracy, the trading rule becomes general. As a trader, you'll never be happy as there is no perfection in an average.
What about Noise? All these dopey bustards trading the ES one minute Chart probably trading Noise half the time, getting whipsawed in and out without rhyme nor reason. Surely MAs reduce Noise.
Wish to eliminate noise, go to a longer timeframe! So es trader trades 1 minute, to eliminate noise, go 5 minute.
Longer the timeframe, the more of the move you miss. Stick a MA on a shorter timeframe Chart and catch move of the move without the Noise?
No, because what you are saying, an average (half of a timeframe) is better than a timeframe. On a 200ma, why not just use 100 day lookback?
Saturday morning here, go things to do, will be back. The point i'm making, yes above 200ma is general uptrend, but its lousy for more accurate timing. When trading, you want to eliminate slippage and ma's are great at slippage.
You know WXY, there is some reason to alot of what you say, but rather than say EWs, say the Market tends to move in 5 Legs. Or rather than Fibs, the market tends to retrace about 50, 33, 66% etc. Then again, saying Markets are predetermined and don't use Stops, well, that's why you're the Boy Wonder!