Claiming that Klout is "meaningless" is a misleading way to convey his point. The author really means to say that measuring influence in more than one area would be better in some situations than a single score. However, given that a large number of people use Klout, and some people get free stuff just for using Klout, it certainly has meaning.
While knowing the horsepower, dimensions, top speed, and durability of a car would certainly be better for some people than a simple "car score", that "car score" might in fact be useful to a large number of people.