I've been using Minio in ZeroFS' [0] CI (a POSIX compliant filesystem that works on top of s3). I guess I'll switch to MicroCeph [1].
[0] https://github.com/Barre/ZeroFS
[1] https://canonical-microceph.readthedocs-hosted.com/stable/
[0] https://github.com/Barre/ZeroFS
[1] https://canonical-microceph.readthedocs-hosted.com/stable/
The use case is fully stateless infrastructure: your file/database servers become disposable and interchangeable (no "pets"), because all state lives in S3. This dramatically simplifies operations, scaling, and disaster recovery, and it's cheap since S3 (or at least, S3 compatible services) storage costs are very low.
The MinIO article's criticisms don't really apply here because ZeroFS doesn't store files 1:1 to S3. It uses an LSM-tree database backed by S3, which allows it to implement proper POSIX semantics with actual performance.
What about NFS or traditional filesystems on iSCSI block devices? I assume you're not using those because managing/scaling/HA for them is too painful? What about the openstack equivalents of EFS/EBS? Or Ceph's fs/blockdev solutions (although looking into it a bit, it seems like those are based on its object store)?