The problem is an example of one of many scenarios where "common sense" does not align with the law. In this case, on what basis would the ATF ban bump/slide fire stocks? If they go the ROF route, then you're suddenly including tons of aftermarket triggers that have shorter resets and lightened pulls, or electronic trigger sets that use microswitches since they would all allow for higher ROFs than military grade triggers. Whatever method is used to ban/restrict them, it needs to be legally and technically sound otherwise, it will provoke lawsuits that can drain the funding available to the BATF for administration and enforcement.
Dude, I know you have taken and do take a lot of flack for voicing your views but it's short little rhetorical quips like this that really don't help things.