Well, first of all, it’s much easier to chain than the standard ternary operator:
string anybody = parm1 ?? localDefault ?? globalDefault;
vs.
string anyboby = (parm1 != null) ? parm1
: ((localDefault != null) ? localDefault
: globalDefault);
It also works well if a null-possible object isn’t a variable:
string anybody = Parameters["Name"]
?? Settings["Name"]
?? GlobalSetting["Name"];
vs.
string anybody = (Parameters["Name"] != null ? Parameters["Name"]
: (Settings["Name"] != null) ? Settings["Name"]
: GlobalSetting["Name"];