IOPS only solves throughput, not latency. You still need to saturate internal parallelism to get good throughput from SSDs, and that requires batching. Also, even double-digit microsecond write latency per transaction commit would limit you to only 10K TPS. It's just not feasible to issue individual synchronous writes for every transaction commit, even on NVMe.

tl;dr "multi-transaction group-commit fsync" is alive and well