There is really no arguing this point. They worked. To the point that freeking _payment_processors_ accepted zero conf txs.
0-Conf requires trust.
Trust that the miners will behave, and not replace a higher fee TX into the pool.
Trust in TX's without any POW
Trust that your node has connected to other REAL nodes.
Trust that your DNS server hasn't been posioned etc.etc.
The white paper states....
12. Conclusion
We have proposed a system for electronic transactions without relying on trust.
In terms of the white paper, 0-Conf is clearly a fail.
No L2, and a requirement for fast confirmations forces you down the 0-Conf route, everyone knows it sucks, but you have to fight the corner because you have no alternative.