It is abosolutely being more explicit. It's being more explicit that (expt b 5) is a unit that forms a single argument in the + form.

This is implicit in

  a + b ** 5

according to a precedence rule between the and + operator, which is hidden in the parser's implementation and in documentation thereof.

Well, the white-spacing

  a + b**5

suggests it. But the suggestions produced by insignificant whitespace can be mere wishful thinking:

  int* x, y; // two C pointers? not!

Speaking of whitespace, also have the advantage of there being multiple ways to split the expression into multiple lines, all conforming to a very clear, simple formatting rule:

  (+ a
     (* 4 (- x y))
     (expt b 5))

  (+ a
     (* 4
        (- x y))
     (expt b 5))

Fully expanded, every term on separate line:

  (+ a
     (* 4
        (- x
           y))
     (expt b
           5))

In this manner, we can write complex expressions that would be quite unreadable in infix, requiring break-up into intermediate temporaries.

We almost have a circuit diagram now with "gates" for the operations: a three input + gate, etc:

     ____
    /    |- a
    |    |      ____
  --| +  |-----/    |- 4
    |    |     |  * |      ____
    \____|-    |    |-----/    |- x
           `   \____|     | -  |
            |             \____|- y
            |   _____     
            `--/     |- b
               | expt|
               \_____|- 5