A best approach to simplification is to click on 'Options' and begin a solution with 'a few steps', then increase the number of solution steps as the additional information is helpful rather than confusing.  The reference of changing '4' to '2^2' is simply a normal practice of prime factorization. 

Prime factorization does ensure that cancellations are properly recognized and its use can be viewed as a "best practice". For example, when working with fractions it is not immediately obvious that "91/28" has any cancellations at all, while the prime-factored version, "(7 * 13) / (2*2 * 7)", has an obvious cancellation of sevens.

The following shows the solution obtained with 'a few steps':