PHP函数array_replace（），为什么参数传递的参数？

The function signature on PHP.net for array_replace() says that the arrays will be passed in by reference. What would be the reason(s)/benefit(s) to doing it this way rather than by value since to get the intended result you must return the finished array to a variable. Just to be clear, I am able to reproduce the results in the manual, so this is not a question on how to use this function. The function signature on PHP.net for array_rep