It turns out the BATF has a metric in terms of tools, skill and time needed to turn a semi-auto gun into full auto, and has banned ones that fall below that threshold, like MAC-10 and -11 clones with fixed firing pins in the bolt face.
And, no, it doesn't catalyze this, or at least no more than allowing the sale of millions of finished AR-15s. Those are a lot closer than a 80% receiver and a pile of parts, "Some assembly required".
