[PommeDeTerre]

There's no such thing as a "schemaless" database. There are, however, different ways of handling the storage and management of the schema.

In the situations you describe, and when using most NoSQL databases, there's still a schema. It's just stored in the minds of developers, in documentation that's correct and up-to-date, in documentation that is incorrect and outdated, throughout application code, and numerous other places.

Then there's the sensible approach taken by most relational database systems, where the schema is centralized, it is described with some degree of rigor, and it can be more safely modified and managed.