Most trading / investing strategies are completely dependent on the time frame you want to work in, and adjust your systems / indicators accordingly. For example, I trade NQ futures, and although you could "try" to use futures for longer term "investing", you are really well advised to keep your time frames within the minutes, hours, or at most a few days. My typical holding period is minutes to hours maximum. Lately, at $20 per point per contract, NQ has moved 100 points ($2000) in minutes, and 500 points ($10,000) during the day. So, I will use moving averages in my strategy, but they are on a
2 minute chart. Shorter time MAs ( 3, 5, 9, 10) for entries, longer term MAs (20 & 50) for trend and direction. The crosses are quick, and the signals are clear.
(Please note that I also use ADX and RSI very heavily in my trading system.) Because of the lag, I could never use MA crosses on a 15 minute, hour, or daily chart to trade for minutes to hours.
For longer term investors ( years holding), you can certainly use a daily chart and watch for longer term MA crosses such as 50, 100, 200 day MA crosses. This strategy has helped some longer term investors avoid big declines after a big rally (like we have just seen, 2008 - 2022) and get in long after a big decline ( such as after 2000 & 2008 declines) or very possibly after the potential big decline that we are currently working out. More so than any MA crosses, the overall economy and investing climate is much more important than any technical system you could use for "investing."
Using MAs to build a trading system is a good start, but should be enhanced with other indicators to fine tune them for trend and direction and entry triggers.
I also agree with
@mashume that some strategies using MAs will not have extremely generous outcomes.