Why Is The Callwhy Is The Slice Method Only A Method Of An Array Instance?

Why is the callwhy is the slice method only a method of an Array instance? The reason why I ask is because if you want to use it for the arguments property of function object, or a string, or an object, or a number instance, you are forced to use Array .prototype slice.call(). And by doing that, you can pass in any type of object instance (Array, Number, String, Object) into it. So why not just default it as a method of all object instances built into the language?In other words, instead of doing this:

function Core(){
var obj = {a : 'a', b : 'b'};
var num = 1;[code]....

//right now none of the above would work but it's more convenient than using the call alternative.

}
Core('dom','event','ajax');

Why did the designers of the javascript scripting language make this decision?