https://en.m.wikipedia.org/wiki/MDMB-4en-PINACA the most common one apparently has been implicated in deaths but there is not any evidence it causes these problems. Deaths were implicated but it doesn't prove it causes it. Since it's on the DEA watchlist I doubt there are enough MDMB-4en-PINACA addicts to seek it out. It's a crappy alternative to the real drug. It's also such a small amount of people.

Snobs don't smoke "bad weed" but if the supply is gone it will be gone. Banning synthetics will easily kill this market, it is a 3rd rate experience that won't be seeked.