The difference here is that the fundamental promise of blockchain is that there is no trusted middleman, so it is not possible even in theory to prevent abuse w

The difference here is that the fundamental promise of blockchain is that there is no trusted middleman, so it is not possible even in theory to prevent abuse without subverting the purpose of the whole system. For existing web2 systems, we can argue at the edges about which things are handled correctly, but at least the mechanism is there.