> REST-API's then are especially suited for acting as a gateway to a database, to easily CRUD and fetch lists of information.

I don't disagree, but I've found (delivering LoB applications) that they are not homogenous: The way REST is implemented, right now, makes it not especially suitable for acting as a gateway to a database.

When you're free of constraints (i.e. greenfield application) you can do better (ITO reliability, product feature velocity, etc) by not using a tree exchange form (XML or JSON).

Because then it's not just a gateway to a database, it's an ill-specified, crippled, slow, unreliable and ad-hoc ORM: it tries to map trees (objects) to tables (relations) and vice versa, with predictably poor results.