If Shea Moisture is a problem it's as likely to be the shea butter as anything else, that is known to build up or weigh down some hair types. This 'protein analogues' stuff sounds like pseudoscience to me, is there any published research on this?

The vast range of ingredients being blamed have completely different methods of affecting the hair, you might think you have similar symptoms it doesn't mean you have the same diagnosis.
2a-2c, medium texture, porous/ colour treated. Three years CG. Past bra strap length heading for waist.

CO-wash: Inecto coconut/ Elvive Volume Collagen
Treatments: Komaza Care Matani, coconut/ sweet almond/ fractionated coconut oils, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss Ultimate Volume, various Elvive
Styler: Umberto Giannini jelly, Au Naturale styling gelee
Flour sack towel, pixie diffuse or air dry.
Experimenting with: benign neglect