What use does if_/3 have?

The predicate if_/3 seems to be fairly popular among the few main contributors in the Prolog part of Stack Overflow.

This predicate is implemented as such, courtesy of @false:

if_(If_1, Then_0, Else_0) :-
   call(If_1, T),
   (  T == true -> call(Then_0)
   ;  T == false -> call(Else_0)
   ;  nonvar(T) -> throw(error(type_error(boolean,T),_))
   ;  /* var(T) */ throw(error(instantiation_error,_))
   ).

However, I have been unable to find a clear, simple, and concise explanation of what this predicate does, and what use it has compared to e.g. the classical if-then-else construct of Prolog if -> then ; else.

Most links I have found directly use this predicate and provide little explanation as to why it gets used, that a non-expert in Prolog could understand easily.