Filesystems aren't efficient for small bits of data.

Like right now I am thinking about a system that has a password reset process and you need to keep track of a user id and a reset token, one or two timestamps, maybe a state variable and a flag or two. That's well under 100 bytes and the cluster size for a typical fs is 4kb or more plus there is the cost of the directory entry. If the OS is Windows it has to ask the Security Manager when ever you open it or delete it which is even more heavyweight.

It's common now for applications that handle lots of little "files" to store them as blobs in SQLlite! See https://sqlite.org/fasterthanfs.html