Lets assume we have a ETH smart contract

It watches at  ETH/USD pair using some oracle like Chainlink

Now, some user sends some amount of ETH to this contract
The contact takes a current value of ETH/USD , for example 3500 and credits the user with exactly 3500 tokens and also burns received ETH

This way our user receives  amount of tokens which  exactly equals to amount of USD he spent

But the total amount of USD spent will not be equal to the total amount of tokens emitted - but nobody would say the exact ratio

How do you think would the the price in USD of such stablecoin close to 1.00?