It feels a bit like everyone is right despite the disagreements.
Almost every market is manipulated (at times), some are never honest - anyone want to take a proper look at silver and gold? They are the most famously and heavily manipulated markets in history, yet a lot of people make money trading them every day and many use TA to guide their decisions.
No TA will ever provide an accurate forecast of anything. No one can see into the future and every market is capable of surprising investors with news and developments.
TA is quite useful and it can be used in any market. It doesn't give you any super powers and it will give you the wrong steer almost as often as it gives you the right one. The fact that it is right a little more often than it is wrong is all it takes to be useful.
TA is not a 'reliable' way to make decisions (in any market), but it is relevant in every market since it seeks to identify trends and sentiment and sometimes it is right.
TA only needs to give you the right direction 51% of the time to be justifiable. We're all dancing around the manipulation in every market. That said, TA is nowhere near as useful as doing real due diligence and looking at fundamentals imo. If you follow the herd you can pick up a few pennies and TA can help you see where it is going and why. But I prefer Warren Buffet's take on it all - "Instead of following the crowd, he looked for undervalued investments and ended up vastly beating the market average every single year. To Warren Buffett, the average is just that — what everybody else is doing. to be above average, you need to measure yourself by what he calls the Inner Scorecard, judging yourself by your own standards and not the world’s."
I've made some cash trading, but nothing like the amount I've made from knowing my own mind and sticking with it. TA works, but it is less accurate in smaller markets. Less accurate doesn't make it entirely useless though.