OK - for me none of those links pass my critical thinking test - they are blogs, articles or commercial outlets that all have a vested interest or at the very least their own agenda.
Some of what they say is correct, some is anecdotelly correct and some is just plain wrong. I am not a qualified chemist (some of the people on here are and know far more about which compounds are damaging than most people!) but have read enough on cosmetic ingredients to have formed my own opinion on much of the greenwashing and scaremongering that exists these days. There are so many truths, half truths and just plain misinformation that unless one is 100% up to speed its really easy to miss stuff. Take L'*h products, often touted as green and ethical, the last time I checked they still used SLS as standard in many products and they are no stranger to using fragrance oil, no matter how their marketing dress it up!
For anyone to say that something does or does not cause damage is always an opinion unless it is backed up with facts that can be quoted and proven. My view, for what its worth, is that almost everyone on SMF - especially the more established members - have been around the block a few times and have seen many of the same questions and same fads come and go. No one can tell you or anyone else what to do but we all have an opinion based on our experience, the experience of those around us, scientific journals, product testing and review, commercial product testing and so on.
There is an opinion - based on experience - that soap used as shampoo is damaging and causes severe hair damage. That opinion does not agree with yours - also based on experience.
Are you both right? Or both wrong? Neither.
No one knows the full background of anyone's hair (unless they are taking a full medical/cosmetic assessment) and what causes someone's hair to fall out or break using soap may or may not do the same to someone else but it doesnt mean that the claim is wrong it means that someones experience causes them to have that experience and they are giving you that information for you to do with what you will.
Just as an aside, if you are thinking of a hair perfume to formulate you could look at something similar to Wild Wash which is used for dogs - bear with me - as that is something that works on a different Ph level and has a no nasties policy.
http://www.wildwash.co.uk/p/4498/WildWash-PRO-Perfume-Fragrance-No1-200ml
Not suggesting you use it but it might be useful as a starting point of formulating your own.