Discussion of a problem in case Modeling

I encountered such a problem in case modeling. I 'd like to hear from you. Use Cases must express the functional requirements of users and communicate with users. If some requirements are user-defined functions, but we find that these functions cannot be implemented by software or there is no need to be implemented by software, whether such requirements should be implemented in the case model.

My personal opinion is that the final case model only provides the use cases to be processed by the software system, rather than the use cases to be processed by the system. However, Case modeling is a process. First, we obtain functional requirements from users. We use cases to express them and refine them later in case modeling, we will remove such use cases that do not require the software system to process. Therefore, I think case modeling should be simply divided into two stages. The Use Case Model in the previous stage is suitable for communication with the use case, which can include some use cases that do not require the implementation of the software system, the use case model in the next stage is suitable for Analysis and Design. Use cases that do not need to be implemented by the software system should be removed.

The above is just my immature point of view. I don't know how you think about it when you encounter such a problem? I 'd like to hear your comments.