Naut Quadra Kill Almost The Penta But Teammate Denies Me

I try not to rage but this type of stuff definitely elicits a response out of me every time. If I think someone has a chance for a Penta or Quadra after they have secured a triple I tend to just either CC or move to block their retreat. I never understood why people try to take away the kills.

Now, if it is the enemy team I try to still fight it out but I don't hand over the Penta