Why there is no -dry-run option?

[itchyny]

In short, dry run option is no suitable for this tool. After executing foo something -dry-run, the user expect the real execution by foo something. However, mmv always requires the user to edit the file names and it can't expect the same changes. The user have to remember the way they edit the file names so it is not that useful. If it should save the renames on dry run to somewhere, it is too complex.