I don't think this scheme provides the "monotonic reads" property discussed in the blog post. Specifically, it would be possible for a reader to observe a new value from r2 (who received a timely heartbeat), then to later observe an older value from r3 (who received a delayed heartbeat). This would be a violation of linearizability, which mandates that operations appear to take place atomically, regardless of which replica is consulted behind the scenes. This is important because linearizability is compositional, so users of CockroachDB and internal systems within CockroachDB can both use global tables as a building block without needing to design around subtle race conditions.
However, for the sake of discussion, this is an interesting point on the design spectrum! A scheme that provides read-your-writes but not monotonic reads is essentially what you would get if you took global tables as described in this blog post, but then never had read-only transactions commit-wait. It's a trade-off we considered early in the design of this work and one that we may consider exposing in the future for select use cases. Here's the relevant section of the original design proposal, if you're interested: https://github.com/cockroachdb/cockroach/blob/master/docs/RF....