[golly_ned]

A file system is simple. Open, read, close. Most tech problems are not that simple. How hard could a filesystem be?

[dekhn]

Locking, checks after unclean shutdown, sparse files, high performance, reliabilty.... are all things that make filesystems harder.

[marsovo]

Erm, most file systems allow you to change data too, right? Hence S3 is emphatically not a file system.

[snoman]

You’ve either never implemented a file system, or just a basic POC of one that nobody used.