I don't think these are bounties offered by the company. They look user driven. Many are hilariously undervalued with very poor specifications making them pretty much worthless (i.e. the example above).

The foundations of social sites, even pseudo-anonymous ones, are built on signaling and skinner boxing with imaginary currency[1]. The prestige from being awarded something, anything, from challenging competition at a community with strong participants is not without value. Quantopian successfully does something similar with HFT, although part of their shtick is accessible data and tooling.

[1] Example: "/u/joebob has a lot of karma/likes/retweets, he must have generated a lot of content deemed valuable by this community to earn that.../u/joebob is actually Joseph Smith, who got a got a great job/exit/customer after becoming internet famous in this forum...I, too, will benefit if I collect a lot of that sweet, sweet karma...I don't think I'll derive as much benefit as /u/joesmith, but getting upvoted for articulating my thoughts is really fun."