Yep, it's a myth that we are the same people. I have always said Somalia is as diverse as any other African country.
These people will deny it but Somalis do have cultural differences. Just recently, we saw Abgaal people chopping each other up, girls and women included in aggressors and victims. Have you ever seen MJs or other Puntites do this? Nope.
When MJs and Puntites fight, it is man vs man. That is it.
The same way we have different cultural dances and dialects, we have subtle and apparent differences in behavior.