ELi5: Why does the regulator not ban retail from FnO

I Understand all the regulators are concerned about the losses retail is piling up in FnO and it has the risk to wipe out household savings in certain cases. So rather than using nudges and setting committees and trying to increase the entry load, why don't just go ahead and ban the retail segment from participating in this segment ?

P.S. This is NOT a joke, neither is this post sarcastic. I am genuinely interested in why not ?