True, I'm not disagreeing with you. However, it's worth nothing that Cockroach DB's consistency model assumes consensus in 180ms, and Spanner assumes similar SLOs at 6ms. Arguably, one could say that the reason why an open-source spanner-like DB doesn't exist in the marketplace with comparable performance is because these types of cards are proprietary and close-source (i.e Google's TrueTime). To your point, Cockroach is much less dependent on highly accurate clocks, but if these PCI-e cards became a common hardware commodity Cockroach can become even faster.

Now imagine a world where distributed DB technologies get so good that the trade-offs between consistency and availability is enough to warrant the use of a distributed DB for mid-sized projects. Right now, these DBs are seen as muscle cars with high cost and high maintenance only for BIG projects. A card like this might be the game-changer.