There is a strong argument for conceptual compression, the idea that every component has an optimum abstraction layer to understand it at, and with that, less-optimum layers for understanding. An ORM that does its job well allows you to take the complexity and pack it away for another day. We can unpack it later when we need to understand those details, but most of the time we'd rather be focused on the details of a domain-specific problem that we're trying to solve, with intricacies that are specific to the domain, that ideally need not become compounded against problems introduced separately by (for example) a persistence layer such as a database, as that makes it harder for the domain experts by introducing another layer of complexity that they must grok in order to build or spec an appropriate solution.
