Yes really. The fact that you can "often just return an object straight from the database" and have it fulfill the functional requirements of your client is just a coincidence, or more likely it's an invarient that you have decided to enforce. What people have discovered (usually very painfully) is that unavoidable breaking changes to either your client representation or storage representation are bound to happen, and when they do if you haven't separated these concerns this will have a ripple effect through the entire application. This may be fine. If your applications are tiny or downtime is okay, then you likely won't care about this. But to casually dismiss this advice as simply always being overcomplicated and overengineered is a grave oversimplification that you may regret someday. Many of the topics in this post fall into this category - people do it for a good reason, and you might not need it, but everything is a tradeoff and "I'm just going to do the stupid simple thing" is not the silver bullet.