Could not agree with your more, just felt it was a necessary addition to your previous commentary. Thank you
If there is a trend then buy a hold and possibly pyramid if you are brave. If there is no trend stay out. This is how big money is made. All else, including pseudo-predictive indicators, mean-reversion, pairs trading, statistical arbitrage and so on is for suckers.
The "quick glance" was not for trading, but to varify that "the indicator peaks and valleys coming before or with the price" was not unique to the chart shown.
That still doesn't prove anything. Design a set of objective trading rules, backtest test it over a number of years with hundreds of trades, then see if you have anything worthwhile.
Assuming you did it properly -- and it was robust and profitable -- then yes. There are still a lot of potential pitfalls with backtesting, but it would be much better than screenshots from charts. I've seen tons of indicators/systems that look good on a variety of charts but fail to be profitable on long-term tests.