He is probably right.
A long time ago (5 years?), we were putting together a software engine to be able to evaluate wine selection choices. However, we were approached by an organization that wanted to be able to use it to scout college football players for the draft, with a specific emphasis on being able to figure out what were the best indicators of a successful NFL QB so that a team does not end up picking someone like Akili Smith.
What we found what that of all the indicators out there, the most reliable was to look at 4th quarter comebacks vs ranked teams. Whether the QB won or not was immaterial. We then put QBs from the past into the same scoring engine, and guys like Tom Brady, Joe Montana and even Aaron Rodgers shot up high while guys like Couch and Smith fell low. Admittedly, that was not the only indicator but it was one of the largest contributors to a successful score. (We are going to leave out the specifics of normalizing data so quality of competition, strength of ones own defenses and the like)
So how is this relevant? Because the same traits that contribute to whether a QB is leading comebacks in college are probably also relevant in the pros and Luck has been phenomenal in being able to keep the team able to make comebacks. So even if he has not developed all of the skillsets enough to be able to contribute to winning in every area, he has the general traits you need to be a top tier QB and he will learn the rest. Luck has shown certain characteristics that the best QBs all tend to have, nothing wrong with recognizing that.
For the same reason that when you see a botched snap with Russell, you notice he often almost calmly collects it and continues with the play. That actually is not common. Both QBs seem to be able to mentally distance themselves from the pressure.
I personally don't get why people care so much about "who is better", QB is a huge determining factor of team success but so is luck (the other luck, matchups, etc.). We have a good team and a good QB. We don't need to worry about whether another team has a good or better QB so we can feel better about our own.
They are both phenomenal players.