The general case adds ambiguity which makes it more of a design choice, rather than an obviously good generalisation.
In the general case of 2 or more comma-separated arguments, is "func a, b" a call with two arguments, or a tuple containing a call with one argument? Feel the same about "x = (func a, b)"? What about when this appears in list syntax like "[x, y, func a, b]", or the argument list of another function like "obj.method(x, y, func a, b)"?
They are easily solvable with a design decision about precedence, but arguably the syntax is a little confusing or worth a warning in all but simple cases.
In the general case of 2 or more comma-separated arguments, is "func a, b" a call with two arguments, or a tuple containing a call with one argument? Feel the same about "x = (func a, b)"? What about when this appears in list syntax like "[x, y, func a, b]", or the argument list of another function like "obj.method(x, y, func a, b)"?
They are easily solvable with a design decision about precedence, but arguably the syntax is a little confusing or worth a warning in all but simple cases.