Of course it's not. But if you have the pocket presence, ability to buy time in the pocket, take rushing yards when they are available, throw from the pocket, read defense, know the offense and defenses inside out, are a team leader, AND you have an elite arm then you can be great. It's not necessary but it's an ability that few other QBs have and would allow him to make some plays that others can't.
And what do you think is the difference between "arm talent" and "arm strength" and why do you think Haner is equal to or better than Rattler in arm talent?