This anecdote is not very surprising to me. Foreign keys are on a scale of DB constraints. I opt to add a maximum of constraints where I can. Adding a date that

This anecdote is not very surprising to me. Foreign keys are on a scale of DB constraints. I opt to add a maximum of constraints where I can. Adding a date that should be in the future - I'm adding a constraint! Did you mess up your time zone conversions & are trying to add a date in the past - the constraint catches it. At some point the constraints are strong enough where with high confidence the following statement can be said: "if the data exists in the database at all, it is correct & complete." This is the "database as fortress" principle, that only correct data should ever be allowed into the database to begin with.