It humanizes the character. It's not needed, no, but it's the hallmark of what separates average movies from great movies.
It's implied he didn't do anything. His father said he let them have 10 years to do whatever. He himself felt like a loser. That's the arc of his whole story...he was not fighting no damn assassins still in those 10 years.
Batman Begins, Bruce was getting his ass whooped
Ironman, Tony had the little janky-ass armors first
And so on and so forth...
This amongst other issues is why I'm saying the movie was mid...it's watchable, but this ain't a great movie. It has the potential but in the pantheon of MCU movies this is above Captain Marvel and below The First Avenger. If that's good-great to you, than we have different expectations for films, especially with what Marvel has brought to us in these last few years.