Litestream/LiteFS author here. I agree that synchronous replication is important and we have plans to implement it in LiteFS. Because LiteFS supports a loose membership model, quorum-based acknowledgement doesn't really work as well since the quorum can change. We have some other pieces to put into place before synchronous replication can work well.

However, I disagree that it's just a "sequence of experiments". There are a lot of applications that can benefit from asynchronous replication. Synchronous acknowledgement of writes can impose a high cost on throughput so many folks use async replication, even in systems like Postgres.