HyperLogLog (or even Count-Min Sketch) will not support some of the requirements of even the Best-Effort counter (clearing counts for specific keys, decrementing counts by any arbitrary number, having a TTL on counts etc.). For Accurate counters, we are trying to solve for multi-region read/write availability at low single-digit millisecond latency at cheap costs, using the infrastructure we already operate and deploy. There are also other requirements such as tracking the provenance of increments, which play a part.