Because it doesn't solve the problem the author is trying to solve? The goal of this is to be able to produce backwards compatible tar.gz files that can be served from a docker registry that also can be on demand streamed instead of predownloaded.
If they just wanted a S3/GCS fuse filesystem there are plenty of open source options out there.
If they just wanted a S3/GCS fuse filesystem there are plenty of open source options out there.