Well that's just like....your opinion man. Here's mine -
They don't shorten the learning curve, they screw it up. Where did I say I don't understand aiming systems? I've studied and tried plenty of them and I've come full circle. I very much regret wasting my time on all that. I'm of the very strong opinion that it will make you worse or at least limit your potential. The ONLY sure method to getting better is consistent and purposeful practice. We can argue about it all day, but I'm 100% positive I'm right...for me and my experiences and what I've in seen of other players I know.
The difference here, is that you have tried and studied a few. I have done that, plus taught a number of systems, used such systems to win many matches, internalized several of those systems to automatic use, improved on some of the systems.
What you seem to fail to understand, is that when learning something, ones overall apparent skill will usually drop due to focus in one area, and lack of focus in other areas. It isn't until the new learning tool is internalized to become automatic that overall improvement is seen.
Just the fact that you even stated that they will limit your potential, shows just how little about them you actually understand. There is no way that they limit anyone's potential when utilized properly.
You say you are 100% right, because you tried a few systems. Sorry, but that is very shortsighted. You can state that you are 100% certain you don't want to use them, but not that they will limit you or even make you a worse off player. You can't begin to state that until you have at least mastered the use of the system you are talking about. Because if you haven't mastered it, you have no idea of the true potential of it.
Bottom line is, you don't like them and don't want to use them, then don't. But don't go around trying to sound like some authority on them when all you have done is tried a few, when you really aren't.