Re: Why forbid "INSERT INTO t () VALUES ();"

I don't see the similarities.  IIUC there isn't a standard mandated function that provides the behavior that the concat function does.  There is an operator but the treatment of NULL is different.  So for concat we decided to add a custom function modelled on another DB's custom function.  Adding custom syntax here when an identically behaving standard syntax already exists has considerably less going for it.  I would say that accepting the compatibility hit while being the ones that are standard-compliant is in line with project values.

David J.