All of that aside I like to be able to see the price action so do not overlay much and at a glance indicators of unrelated types so that their agreement is more powerful. I also draw in an occasional level or trend line.
Agree with number 3 overall and add when you put together a mix you are comfortable with, stay with it.
To me, it's not that you can't but rather that you have to find the correct way.
I think there is a common mistake people make between Price Action and Price Patterns, I personally know a lot of price action traders who use no indicators in fact some even use just line graphs and interest rates.
I sometimes use a simple RSI at key levels to execute but I never justify a trade because of it. I just use it to identify fakeout levels and retail traps, I trade the above mentioned Price Action which based on interest rates and commercial flows. (which I learned from the "textbooks")
I personally think a more fundamentals (again theres a misconception between economic data releases and economic drivers lol)
but nonetheless nice thoughtful read mate.
Thanks for your feedback and have a good trading week :)
Be aware that you could build indicators with whatever data so it is not necessarily past-data only. That said, what's wrong with past data? Most predictive models in scientific research are based on past-data. Take also weather forecasting algorithms, they were developed on past-data and they are exceptionally good these days. Machine learning? Same thing, based on observation in order to become more accurate in the future.
This is just to say that I don't see any particular limitation in working with past-data indicators. Of course they must be well engineered.