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, growing out mechanical and chemical damage = breakage and very high porosity. Past armpit length heading for waist.
Treatments: Komaza protein, Komaza Matani, coconut oil with sugar syrup. Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss ultimate volume
Styler: Umberto Giannini jelly, Boots curl creme, Rockin RInglets
Experimenting with: Mega-Tek, Curl Harmony reviver, Elvive Full Restore 5.