You can indeed model relational domains using document stores, but soon you'll start having keys everywhere to glue the different documents together. This may

You can indeed model relational domains using document stores, but soon you'll start having keys everywhere to glue the different documents together. This may not be that big of an issue if you have a few different types of entities and you're not keeping that many relationships between them. But you're still going to face problems when you need to change the relationships, an issue which is trivial to resolve in a relational DB. If there are more than a few relationships and they're even just moderately unstable, you've probably made a critical mess of the application.