No, your economics isn't lacking.I'm a PhD economist, and in light of Venezuela's announcement, I've been trying to figure out exactly how you could peg a crypto.

The only way that I can see is to would be to disallow trading on external markets. In other words, Steem is traded on exchanges, while SBD can be sold only on steemit for exactly $1. (And the conversion between steem and SBD also only occurs only on steemit).