Other than the fact that their explanation of how the old style linear converters work is wrong (or at least a bit misleading), the conclusions are correct. They just are not correct for anything built this century.
Linear converters were designed when the only electronics in an RV were the radio and the battery operated black and white TV (if you were a high roller). They power lights just fine, and did an adequate job with the battery, when the job was to charge overnight to be ready for the next day of travel. It's just that modern units are *far* better at battery management.