It's simple. I'm just saying that (for most frameworks) it's a lot of work and boilerplate. It's also easy to miss individual cases during code review, etc.
You kind of miss the part where he says "Usually implemented transparently for the data layer API clients." Transparently as in no work, no boilerplate.
I guess your mileage might vary, but Java has JPA/Hibernate, and .NET has Entity Framework, and they both make it easy, so I'm going to be surprised if any major framework or language doesn't make this easy.
