These folk doctrines (not drinking Coke, staying in church clothes all day Sunday, not watching TV, etc.) are akin to being allotted only a certain number of steps on the sabbath day . . .
The problem with building a hedge around the law is that, after a while, people think the hedge is the law.
Comment #24 by Shadow on Obnoxious Folk Doctrines: the Unstoppable Force - Stephen Marsh (Mormon Matters)