Refuting the "it doesn't scale" argument with a data from a blog that showcases a single workload (TPC-C) with 200G+10tables dataset (small to medium) at 2vCPU (wtf) machine with 16 connections (no thread pool so overprovisioned) is not quite a definition of a scale at all. It's a lost experiment if anything.
I did internal benchmarks at ClusterHQ in 2016. Those benchmarks showed that a tuned ZFS FS of the time had 85% the performance of XFS on equal hardware (a beefy EC2 instance with 4 SSDs, with XFS using MD RAID 0), but it was considered a win for ZFS because of the performance difference when running backups. L2ARC was not considered since the underlying storage was already SSD based and there was nothing faster, but in practice, you often can use it with a faster tier of storage and that puts ZFS ahead even without considering the substantial performance dips of backups.
The guy did not have any data to justify his claims of not scaling. Percona’s data says otherwise. If you don’t like how they got their data, then I advise you to do your own benchmarks.