Why do authors use causal relationship in play's

I believe authors use casual relationship in plays because its a logical pattern, where a clear action (cause) has a reaction (effect).

Most of these patterns happen to show how the main character has emotional reaction perhaps through dialog, gesture, expression, or physical sensation. The character makes a decision on what to do next. The character are goes through events that reveal motivation setting impact, conflicts.

these are the reasons why authors use casual relationship in play's