Whats with the NASCAR rebel flag policy?

It has been a rule for a very long time that the rebel flag is not permitted to be used on any car or apparel. why? thats stupid. just keep strayin away from ur roots NASCAR. And a couple of the big shots in nascar said if they cud they wud ban the fans from flying it in the infield and parking lot? why? if u say its racist, u are very wrong. it is not a symbol of hate. this is not against NASCAR, i love nascar ive been watchin it since the early 90s. I just wanna know why their scared to use it