Here some benefits about it:
1. Access to metrics details. SEOmoz typically shares information on how it calculates Page Authority. In addition, anytime SEOmoz tweaks the algorithm it uses to calculate Page Authority, you can be sure to find announcements with further details.
2. Frequent updates ensure accurate metrics. SEOmoz continues to update Page Authority in shorter intervals than Google updates PageRank, thus ensuring that you get the most accurate and up-to-date measurements possible. This is especially beneficial if you post fresh content frequently.
3. Granularity helps measure progress. Page Authority is rated on a more granular scale than PageRank, as it assigns points between 1 and 100 (vs. PageRank’s 1 to 10 scale). As a result, it is easier for you for to evaluate your progress, or spot emerging challenges, as you make adjustments to your web pages.