Tobbe
I don't think this needs to be explicitly mentioned but it's good if it is done.
Everything that is at stake here can be traced back to reliability and trust.
If you have an agreement you keep it -> reliability.
The other side trusts that it will be kept. -> Trust
If one of these is not there, it is useless, no matter if a belt is worn or not.
If both are present, a belt is not necessary.
Sure, some are of the opinion it gives more security. But to me it looks like wearing a jumpsuit with a belt and suspenders. Sure, it's safer but not necessary.