1. Durability extends to the client. Replicated db might ack a write to client, but what if that ack gets lost on the way back over network? If client talks to the DB over simple HTTP, the write might first look like a failure. Can the client retry?

2. Human perception times are biological and don’t change much. But everything in the tech stack has gotten so so much faster since the 80s. Throughput matters, sure, but latency (relatively speaking), is much less of a constraint now than it was.

You can make writes faster and part of that is by not dealing with schema resolution but you do push the work somewhere else there too.

I guess the same principles apply on many different levels, from when you write to the file system up to how you deal with conflicted data types during data ingestion.