Isn't this a vital threat for bitcoin? These backing issues are preventing bitcoin from mass adoption. It shouldn't be a scam scheme. But if we don't have these stable coins, these will not happening for sure.
Why stable coind can't help bitcoin to be recognize? As far as I know, there are some exchange who do not accepts USD so you will first exchange your USD to other stable coins then you will use that STABLE COIN (like USDT(Tether)) to buy some Bitcoins.
For me, stable coins is not really threat for Bitcoin as long as they are 100% transparent, or really backed/pegged with some national currency like USD.