In the future, you may want to read the OP carefully in order to avoid disqualifying yourself like you did in this case. To quote the OP on stablecoin: "From then on, we keep track of how much USD has inflated/deflated using something like CPI or the Billion Price Index or even a combination of indices". Have a look at the wording: The idea is to introduce a single point of failure, either through CPI or Billion Price Index. "Or even" multiple points of failure through a combination of indices. But a stable, decentralized system is completely out of the question. Basically, stability is completely sacrificed, but ironically it is put into the name...
I know how stablecoin would work. The source of conflict may be our definition of "single point of failure".
To simplify, let's use goldcoin. Miners would report the price in goldcoins of gold (getting information from various exchanges and probably averaging them).
You may think that gold and goldcoin exchanges are the points of failure in this case, but it can be discussed.
As I see it, instead of a CPI index miners would report spot prices from various exchanges and then the price index would be calculated from those spot prices.
I don't think that you can target the price of any commodity or that you can have a totally stable coin just through changing the money supply, but it could be more stable.
Don't know what the OP is, but if you mean this thread, yes I've read it.
Maybe you didn't understand me because some of us have been discussing some topics of this thread in other threads.