I learned about scab hair in Pamela Farrell's book, "Let's Talk Hair."
http://www.amazon.com/Lets-Talk-Hair-Personal-Consultation/dp/0939183021
Given that she worked extensively w/women with natural, relaxed and transitioning hair, at a time when NO ONE was trying to work w/us to help us transition (if we desired), I personally believe she had the expertise to speak to the issue (of scab hair). She probably saw it personally, worked w/clients that had it, etc.
I'm not sure why you feel people would be addressing the issue somehow, given that so few people were addressing curly hair at all. Fewer still were addressing our curly textured hair and how to care for it, and relaxers, transitioning, etc. Much of what we've learned about how to work with curly hair, and aa curly textures, has come to light in the last decade or so.
Professionals in the cosmetology industry, weren't learning a thing about how to deal with curly hair (other than how to straighten it). People in cosmetology school don't learn how to care for our hair--such as issues that can arise from relaxer use, heat styling, etc. The predominate population cosmetology students are taught to care for, are those w/naturally straight hair. So given this, how can we expect that doctors or other health care professionals to somehow have this knowledge?