There are a bunch of cryptocurrencies which use DAGs. All of them claiming to be 100% unique and innovative.
I saw one which claimed it was "impossible to 51% because it's a DAG and both chains just end up on the network"
No. That means either you don't have consistency (which means 51% attacks could be theoretically implemented with way less than 51% of the hash rate) or that the consensus of which transaction are valid can be 51%ed.
Iota is even worse. Doesn't even try to have a distributed consensus, just uses a centralized validator.
I saw one which claimed it was "impossible to 51% because it's a DAG and both chains just end up on the network"
No. That means either you don't have consistency (which means 51% attacks could be theoretically implemented with way less than 51% of the hash rate) or that the consensus of which transaction are valid can be 51%ed.
Iota is even worse. Doesn't even try to have a distributed consensus, just uses a centralized validator.