Well, yes and no. It is centralized in terms of how the data is interpreted, but all the data I gathered here I did so from the blockchain. That data exists as records in the custom_json. If they didn't fulfill their commitments and started faking the numbers (either on blockchain or off) they would lose credibility with their community.
I do think the interest relates to many things people want to see on STEEM: fun, activity, engagement, novelty, excitement, potential for future rewards, potential for future gaming, etc, etc.