The evolution of ESNI into ECH has been slow but basically encryption of just the SNI would not play nicely with the rest of the protocol. So more had to be enc

The evolution of ESNI into ECH has been slow but basically encryption of just the SNI would not play nicely with the rest of the protocol. So more had to be encrypted but that meant a deeper interaction to analyze. It's also dependent on a new kind of DNS record and the original design wasn't great for DNS load balancing. Some tweaking had to happen there too.