The continued presence of prime factors represents on the one hand a best practice because its use does eliminate many cancellation omissions and errors.  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.

6/3 reduces to 2

3/3 reduces to 1