The funny thing is if you look at the actual volatility it isn't that high (its about twice Bitcoin the last time I measured it). The problem is not 'volatility' it is that it is just heading down, likely in large part due to some of the reasons you state. -99% is not a 'normal' fluctuation, it is rejection by the market.
I really just don't agree that any particular "network effect, liquidity and low volatility" is required to back a stablecoin. It is required if you define a "stablecoin" as something that is extremely stable all the time (say to challenge the dollar), but you don't necessarily need that to be useful. SBD has significantly lower volatility than STEEM even now, and that is very useful to SPS for example. A developer or business can handle changes of 10% or 20% in a month a lot more than 10% or 20% in a day and 50% or more in a month. (SBD also has some other desirable properties even in its current imperfect form, for example while in haircut mode, if you hold it, you are essentially guaranteed to see it return to $1 eventually, as long as Steem doesn't entirely fail, although it isn't at all clear when.) Every other experiment with crypto funding systems like SPS has experienced the high volatility of the native token as being a major problem. SBD even with its current limited degree of stability does a better job, and probably having a much lower volatility token (even if not perfectly stable) adds value to the platform in other ways too.
RE: (Very) Basic stuff Steem needs to fix: my personal list