as a frog, I don't disagree with what NL does. It's very reasonable.
keep in mind : THERE IS NO FREE LUNCH
just give you an example : everyone hates Microsoft - Windows is buggy and expensive. But how many people use Linux, even though it's FREE ? I myself is a software engineer and develop system software on Unix/Linux, but I still run Windows at home, I just don't want to spend time re-compiling the kernel or searching for the driver.
You can argue that MACD, RSI is all open, right. TCP/IP and Ethernet are well documented and open, but do you see anyone developing his own router or network card? ss7 is a standard, but did you see anyone develop his own telephone ?
Think in this way, like TOEFL class, Can you do it without it? absolutely yes! but did you take one? Maybe yes. So why did you pay for the class? ....because you had a wish...you wished there might be a magic...maybe it only wasted your time, but still a wish , until you tried, you don't know.
Same thing here, let people try. There is no free lunch, it means you have to work hard, it doesn't mean you have to pay more. Learning from experienced and history is good. but if something is said too good, better be cautious.