LOL! This reminds me of how my sister-in-law once complimented me on how healthy and thick my hair looked and asked me specifically what conditioner I use. I told her Giovanni 50:50 Hydrating Calming Conditioner with oil and honey added for the DC, VO5 as my RO and Shea Moisture Restorative Care as my LI. She wrinkled up her nose like something smelled bad then told me my hair would "fall out" from using all those "white people" conditioners on my hair and from leaving conditioner in my hair instead of rinsing it out. Keep in mind, though she is natural (she heat straightens regularly), her hair looks perpetually short, thin and damaged on a good day.
On another note, I remember reading somewhere (maybe one of the forums here in CT) that before hair conditioners were invented/discovered that people applied fabric softener to their hair after shampooing then rinsed it out to help soften the hair after cleansing. I would imagine that leaving fabric softener in your hair might have some ill effects on your hair so maybe that's where the belief that leaving conditioner in your hair causes it to fall out comes from...