Selective views of the facts...
"other replication products from, for example, NetApp, are based on snapshots and don't offer continuous data protection"
EMC & Hitachi offer continuous replication, synchronously or asynchronously depending on configuration.
"while having more of a performance impact on the source server than Zerto's low-touch replication"
Both of the above have no performance impact on the source server as it's handled within the SAN.
That said, it's an option for those who can't afford the enterprise level storage solutions from EMC etc, particularly because it allows heterogeneous storage solutions, but marketing it correctly would build more trust.