I'm basing my thinking off of the SBD section of the Steem whitepaper. As for the SBD price never being less than $1, you can see in the chart that there are times when it is less than $1, but it typically isn't less than $1 by much and isn't less than $1 for long because, per the whitepaper, there is a 3.5 day process where you can convert SBD to Steem which attempts convert 1 SBD into $1 worth of Steem. However, this isn't a guarantee because there are some variables involved (which I don't fully understand yet) where you don't always get exactly $1 worth of Steem after the 3.5 days conversion process.