> It avoids an entire round trip to the issuer's backend and back, which are often still somewhat expensive and slow, given the legacy systems and connections involved.
Not if done both client-side and server-side.
Right now, if I swipe my magnetic stripe, then terminal will reject it if the stripe has the magic bit set. If the magic bit is clear, the terminal will (eventually, but usually while the customer waits) send a message to the network saying that the card was present and asking for authorization. The network responds. No additional round trip would be needed for the network to deny authorization if the chip was not used.
Not if done both client-side and server-side.
Right now, if I swipe my magnetic stripe, then terminal will reject it if the stripe has the magic bit set. If the magic bit is clear, the terminal will (eventually, but usually while the customer waits) send a message to the network saying that the card was present and asking for authorization. The network responds. No additional round trip would be needed for the network to deny authorization if the chip was not used.