Before computers and electronic calculators, traders really learned Price structure, they understood the whys much more than now, you carried a charting book, graph paper, ruler, pencil and sharpener, ahh the good old days except for brokerage costs. Often times it was like Fibonacici, it worked cause many would do it/volume pushes the markets, but it is still true today, many people including myself use trendlines and we would not use them if they were not effective. We deal with price so there is no delay than like indicator based methods, plus risk is much less that those require price doing breakouts on momentum as that requires greater to greatest risk and many times more false signals. So you can see benefits of price either going to hold trendlines or push through and take small loss OR develop reversal entry to go other way cause trend failed or completed. Is it any better than moving averages? That depends on you knowledge of chart reading and back testing. Pure chartists will say nothing better, but there are skills of learning how to draw them and knowing they don't go forever. I have developed systems where only signals are trendlines and depending on timeframes, can have 50 trades plus a day on 23 hour instruments, most would disagree but there is skill needed on drawing them so you have less losses and being able to identify failures and ends of a swing(trend).
