The UTXO model is very restrictive because it forces all state into the transactions themselves. Every state modification becomes a new output and must make a full copy of the prior state + modifications.
If you attempt to implement a market with bids and asks as UTXO outputs, then the person who creates a "taker" must spend the inputs and create new outputs.
Two people attempt to construct this transaction "at the same time" and only one of them will succeed. The other party will find their transaction was generated with inputs that are now "spent" and therefore invalid.
At this point the person that generated the transaction either has to attempt to build on the unconfirmed transaction or wait until the next block.
The UTXO model is very restrictive because it forces all state into the transactions themselves. Every state modification becomes a new output and must make a full copy of the prior state + modifications.
If you attempt to implement a market with bids and asks as UTXO outputs, then the person who creates a "taker" must spend the inputs and create new outputs.
Two people attempt to construct this transaction "at the same time" and only one of them will succeed. The other party will find their transaction was generated with inputs that are now "spent" and therefore invalid.
At this point the person that generated the transaction either has to attempt to build on the unconfirmed transaction or wait until the next block.