No joke. Prior to the Clinton ban NOBODY wanted para stocks unless they were actually going to jump out of airplanes. We used to joke about HK slide stocks and called them "meat tenderizers", especially on .308 91/G3 models. They were heavy and really chewed up your shoulder, but once you took them away everyone had to have one.
Bayonet lugs only meant things to WWII collectors, nobody was really buying bayonets for the Colt carbines, they didn't fit anyway.
But we probably should remember Colt voluntarily neutered their rifles as early as 89 removing bayonet lugs and in some cases CAR type stocks.