Reason #2:
You are G‑d’s warrior. And just as G‑d cannot tolerate falsehood, so too you, as His fighter, have a moral obligation to search, find and publicize your fellow’s secrets, so that he should not, heaven forbid, receive false respect and feel haughty.
In short: It’s all in the name of G‑d.
Reason #3:
It is a custom amongst families and communities from way back when, that on many an occasion, especially around the dinner table, a human sacrifice is laid on the table/altar and slaughtered with verbal knifes and daggers.
In short: We don’t mess with tradition.