What are the advantages of using a value such as "Productivity Ranking" over the commonly accepted values of "XP/Hour"?

What are the advantages of using a value such as "Productivity Ranking" over the commonly accepted values of "XP/Hour"?

 

.........sounds better........and its not aimed at just high end players, its a way to put exp gains in a true order, at lvl 20 you may have a rating of 20, but at 89 that same action may have a rating of 55, its a way to show how you would advance with the same action at different levels. It may not be worth farming a mob at say level 40, but when you get up to level 70 you maybe able to kill 3 times as many in the same amount of time, but then killing a higher level mob may give more exp per kill, but it takes longer to kill, with exp per hour your looking at stats from a 99 not a 40, so when it comes down to it, exp per hour can be a way to show it, but most dont bother putting up exp per hour at different levels with the same skill.......did i mention that it sounds better?

Productivity is the amount of output per unit of input (we usually use xp as the standard unit for output and hours as the standard unit for input). Xp/hour is a measure of productivity, and that's exactly what you're measuring; you simply make the distinction that it's at x level rather than 99.