Sometimes you don't need to use model instead of entity, and then save some data into entity and persist it. It means you cannot use it in Sylius ResourceControllers, because your model must implement ResourceInterface, create dedicated ResourceController, Repository, Manager, and model cannot do it.
If you want it, this means you doing it wrong, because it violated CRUD principles. The best solution is to use Symfony Data Transformers https://symfony.com/doc/current/form/data_transformers.html , add it to your form, implement transform() method, where it will create your model/DTO object from entity, and reverseTransform(), where DTO will be converted into Entity object.
