Klout acquired by Lithium

Surprised the exit happens at the relatively low price of $200M [1]. Klout had about 500 million users from what I understand. While monetisation might have been tough with deals, Klout got so much data. So much talk of 'big data' but it does not seem to be worth so much... or was there some founder fatigue at play here after almost 6 years of existence?

[1] http://www.crunchbase.com/company/klout