Oils are "emollient soluble" or "oil soluble", (simple chemistry, like-dissolves-like), which means they are rinsed out with conditioners that contain emollients/oils (fatty alcohols, conditioning agents, emulsifiers..). Silicones, on the other hand, dry into a solid film, (even most mild silicones are only water/emollient soluble within the bottle and NOT once deposited onto hair), so they must be dissolved by a chemical surfactant. Much like lime deposits (showerscum), silicones require high ph, very alkaline and harsh chemicals to remove...

FYI, I mix oil with my LI, (4 drops grapeseed to every quarter sized dollop), to avoid "greasy hair" and maintain the benefits of sealing. I also use the occasional mild coney LI and cleanse with coco-betaine at the end of the week. I believe only dimethicone MUST be removed with SLS (sulfates). Mild cones, (like bis-amino propyl dimethicone, PEG-silicones, amodimethicone or phenyltrimethocone), can be removed with coco betaine. But watch out with how often you "low poo" with this, cuz it can be striping to your hairs natural oils (aka protective barrier). Hope this helps
3B, Fine, Normal P, Normal E, Low-Med D
LowP: Kinky Curly Come Clean (50% EVOO)
NoP: As I Am CC
RO: Suave Coconut, VO5 Shea Cashmere
LI: KCKT or CJBCLI or HETT/HENOYF (w/ 8 drops GSO)

"To much is given, much is expected"