A lot of dumb laws exist just to keep the government happy and to oppress the people. I would bet you even if these stills were made legal tomorrow, you would not have a rush of people to set one up. Those who had them would continue to have them. They are too complicated and troublesome to setup for the average person.

Another dumb US law: short barrel rifles. Apparently, those were restricted when they were planning to ban hand guns back in the day, to close a loophole. The handgun ban fell through. So now, for no reason, the less concealable short barreled rifles are more restricted than perfectly concealable guns.