Most of the developers of Steemit still want to pin it down (I don't know how) so it will look more secure for people to start using it, instead of treating it as a scam that will one day burst like a bubble. The value of STEEM is the only thing that is supposed to change, and even then only for reward payouts withing Steemit. Meaning, the only fluxuation is "supposed" to be the amount of SP you gain, not its value in the market.