How do you update entity display mode to show a newly created field by default? It is easy with configuration import, but what if you need to use hook_update_N?
In Drupal, it is possible to create entity types with multiple options - with or without revisions, fieldable or not and these options have a different performance impact when dealing with functionalities that handle a large number of entities in a single process, so you would want it to be as fast as possible.