The question Is there any guideline on how to choose the objects to be modelled? is closed for being unfocused:
If your question has many valid answers (but no way to determine which, if any, are correct), then it probably needs to be more focused to be successful in our format. This can often be fixed by breaking the post into multiple questions, or by focusing on a specific part of the problem.
Can you give more detail why this question has many valid answers but no way to determine which are correct? The already two answers of the question are consensus. The only interpretation to explain the close reason I can think of is the verbose conversation in the question body. I was aware of that, but decided to write it as is anyway because I don't know how to rewrite it without losing the nuances, details, contexts in the conversation. And even so I don't see it worth the effort. I'm looking to hear the opposite thinking.