Instead of regular centralize stablecoins, why we don't have a stablecoin with its own blockchain or a token where anyone can mint or redeem that stablecoin using ONLY Cryptocurrencies at the market price.
For example if I have 1 Eth and want to mint it into Xusd (community stablecoin) it goes like this example:
If Eth market price = $1000 I send 1 Eth to this blockchain or contract and I receive 1000 Xusd.
And it can be redeem for any Crypto at market price,
If Eth price = $2000 I send 1000 Xusd and get 0.5 Eth.
What you are proposing seems to me very similar to what has already been implemented. These are wrapped tokens that are tied to the cryptocurrency for which they were issued. For bitcoin there is Wrapped BTC (WBTC), for ETH there is Wrapped ETH (WETH).
I think you got his proposed idea wrong and if I am right he is proposing something like DAI, a stablecoin project pegged to 1:1 US dollar but using Ethereum as collateral to maintain the pegged value which makes it one of the few existing decentralized stable coin project.
But I don't know how is it possible to have a native blockchain for such project will work.