[jryan49]

Why not, is because you want ACID guarantees (ie, what if two people are editing a file at once), ability to scale, or a query language.

[xyheme]

That all can be achieved by using file system as database.

Not even complicated to implement.

See couchDB for how to handle "what if two people are editing a file at once".

[jryan49]

You're not getting that just from the file system though. Depending on the performance requirements and use case it may or may not be complicated. You are going down the rabbit hole of creating your own foundation for a database at that point.