No. They aren't the shoulder thing that goes up, either. You're likely thinking of pistol braces. Maybe learn what you are talking about before posting an opinion on it? Or run for Congress, since most of them don't know what the hell they are talking about either, and enjoy passing laws regulating things they know nothing about.
Maybe the article that you posted can explain it to you:
"Despite all of these actions, President Trump’s first term saw one clear Second Amendment policy failure. Under his administration, the ATF arbitrarily reinterpreted the federal definition of “machine gun” to include bump stocks, banning their civilian possession and requiring owners to turn in these devices. It did so even though bump stocks do not modify the mechanics of a semi-automatic firearm, and the agency has no authority to change the meaning of federal law.
Regardless of one’s perspective on the desirability, constitutionality, or practical effectiveness of banning the civilian possession of bump stocks, the way in which the ATF went about doing so is troubling. When a largely unaccountable federal agency feels empowered to effectively rewrite statutes in order to create new gun control laws, it poses a danger to the entire Constitution, including the Second Amendment."
