Moving averages are generally inferior as indicators because of lag. The technical term for lag is group delay because MAs are just lowpass filters. Look at the work of John Ehlers for some of his low lag and near-zero lag MAs.
I don't like "moving average crosses" of any stripe. They are 2nd derivatives of price. Any trader worth his salt should have "seen it" before the cross. The concept of "Moving Average As Support/Resistance" has some validity, however.
Faster the indicator whether moving averages or trendlines, more false signals. Moving average crossovers work in the past and unless you optimizing each second, they fail. You can look on a bell curve of optimized crossovers and a viable system should have good values above and below the best, whereas crossovers, never have seen much of this to work for any length of time, and no one would be predicting it work in the future. Moving averages can be thought of like Parabolics, price above and rising is an uptrend, price falling and above the Average is a retracement, and opposites below Average is the same except faster normally. Risk management- smallest risk for these types of systems of bouncing off moving averages, parabolics, Bollinger Bands, Keltners, Clouds and trendlines are right on indicator, price holds or not. At some area when price goes through, have to an area where one's definition says trend has changed, tighter to the indicator will produce more failures but further from indicator, protective stops often are larger. If one is a scalper, best trades are closest to the indicator, whereas long term, more of a confirmed approach of the indicator is relied upon. Many laugh at BTFD/STFR, but this often best areas to trade providing you done enough testing if it matches your personality.
Saltynuts, I use the most popular EMAs in my trading as places or EMAs price to be aware of when I am managing a trade. Once I enter a trade I want to know of these EMAs on the higher time frame or near my stop loss or will prevent my profit target from being hit. Sort of like a support or resistance thinking. I day trade, so I don't buy and hold for days like that. As far as system involving moving averages. It could be possible, just have to back test some simple ideas and review the odds of the idea making money in the past.
No matter how you have bought into an instrument or why or for how long, attention to at least one MA can help avoid the worst of a bear market. I would only take a long-term trend-following buy if all four of these criteria apply - 1 - 20EMA is above 50EMA 2 - 50EMA is above 200EMA 3 - 50EMA is sloping upwards 4 - last close was above 50EMA Once I'm long, if any one or two of these fail, I'm probably going to sell. If two or three fail, I'm definitely getting out. Same applies to index chart for stocks. Hard to justify being long US equities of the S&P doesn't meet 1-4 above.
Moving averages of whatever length or however calculated are still nothing but squiggly lines. It follows price up and over and down and around but price takes it own path where it will go regardless of whether a squiggly line is there or not.
though moving average are great for dynamic support and resistance, I use them to know the major direction of the price and also to find entry points.