Only if things were that simple :) Calvin avoids the need to track clock accuracy by making every transaction go through a single consensus leader which inherently becomes a single point of bottleneck for performance and availability. Spanner and its derivatives including YugaByte DB chose not to introduce such a bottleneck in their architecture with the use of per-shard consensus — this means caring about clock skews for multi-shard transactions and not allowing such transactions to proceed on nodes that exhibit skew more than the max configured. The big question is which is more acceptable: lower performance & availability on the normal path OR handling offending nodes with high clock skew on the exceptions path?