Nobody is claiming to be selling stock in companies. They're claiming to be, and are, selling synthetic assets that track that price movements of stock.
It's not really. They're transparent, auditable, and typically they're designed to use over-collateralization to prevent liquidity problems, but they're not 100% immune to them and still count as bucket shops IMO.
But they're absolutely not fraud or "fake stocks".
The spread betting companies in the UK work very much like bucket shops and are not only legal but tax free. Unlike these blockchain things they are regulated and unlikely to run off with your money.
I imagine very few people would be interested in smart contracts if it became a defacto legal standard in the US and Europe that these contracts are unenforceable.
Of course this doesn't address contracts being written out of Russia or traditional financial havens, but how valuable is a vehicle which can't be used to move assets into or within the US or Europe?
I think the question of enforcement is the wrong one.
The greater Ethereum community accepts to put restrictions into place, or the US/EU/China puts sanctions on Eth owners and traders. You get to either move to Sealand, or accept restrictions.