2003 Ford Taurus will an o2 sensor cause this car not to start?

ok, will an o2 sensor cause this car not to start. or any car in this matter.. i am not having this issue, just having a debate due to an o2 sensor not starting a vehicle.

i say even with a bad o2 any vehicle should still at least start.

he says he has seen a couple different vehicle's not start because of a bad o2.

what do you guys think ????

thanks