Essentially, this game is based around the community, and the CFC games are a fun medium for said community to interact and expand. Those who have no sense of community wouldn't be rewarded with a currency implemented for that purpose (to promote activity).
If I'm understanding your concern correctly, Zero, you're thinking of the shy/ultra-reclusive players or players without a lot of time to spend recording that would gladly sign up if they felt comfortable/free enough to do so (and not necessarily people who don't want to sign up). The response is that this is why there is such variation with the games. People without a desire to post much or who don't have the time to check logs might not want to play in an alt hunt like Sharkticonado or May the Fourth Be With You, but all they'd have to do to participate in a scalp hunt is sign up so kills from their characters count
It'll be slower for them, but not impossible.
Also, the more events people sneak into, the more comfortable they'll likely feel with joining more, so a reward system is good incentive all around, in my honest opinion.