Why would you NOT set IGNORE_DUP_KEY to ON?

Question

IGNORE_DUP_KEY = ON basically tells SQL Server to insert non-duplicate rows, but silently ignore any duplicates; the default behavior is to raise an error and a

Answer 1

It can be used as a sanity check. If you know that there should be no conflicts leave it off and it will fail fast on bugs. OTOH for ad-hoc console sessions, I see your point.