Just a quick response in that Klout is, in fact, important for two reasons (BTW I wrote the first book on influence marketing in 2012 and have probably studied Klout more than any person alive!)
Number one. The reason interest in Klout has fallen is that it has become less controversial, in fact they were acquired by Lithium and they are nearly invisible today. Back in 2012 they were controversial and that is why there was a peak in interest as your chart shows. However, if you did the same Google trend search for “influence marketing,” you would see a hockey stick in the opposite direction. The fact is that many companies are using ad agencies and are using algorithms to determine “who is an influencer” which means, who is going to get paid by companies. Here is the dirty little secret — almost all of these agencies are using some form of Klout or a variation of the Klout formula to find influencers. So, if you want to be found, you need to understand what drives Klout. Even if your friends don’t know what it is, the people making decisions do.
Number two. Klout is not necessarily a measure of influence, per se. Your example of gaming it shows that. But what Klout really is, is a relative comparison of a person’s ability to spread content. Today power on the web does not come from content. It comes from content that MOVES. Companies do not want content. They want transmission of content. They want people to see it and share it. A person with a high Klout score shows that they can get their content shared, and that is an extremely important measure in today’s marketplace. Hope that helps.