[devonin]

I can't see why the credits you earn from a song should have a cap

Because once the credit system is a little less prone to exploding, the potential exists to start offering more than just the secret genre in exchange for credits. I remember talk of buying subscription time, or maybe even merchendise with credits.

Regardless, if anything really substantial is ever going to be available for credits, they have to at least attempt to limit how large a total people can rack up easily.