I disagree partially. I do agree that modeling your domain in programming language objects and then transforming those objects into data stored relational tables (OR Mapping) is not a great design. However, DDD can also be done where the relational database is the model of the domain, and the application is merely a set of functions that execute SQL and transform the results. So based on the application two approaches for persistence are possible:

1) Model the domain in the programming language, and store data as opaque blobs. 2) Model the domain in relational tables, and use the application logic to extract and transform the data.