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?
Over time you will extend functionality. Locally things work but then you need to start planning how to update existing environments and then interesting problems will arise.
The hardest thing in software development - is naming. Whether it is a variable, class name, or field naming in Drupal, it might be complicated. I'll write about my naming convention in Drupal that I will use daily basis and what are the benefits.
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.