History is a critical element of Star Wars.
As our real-world society studies the past and learns to apply critical lessons towards paving the future, the Star Wars universe has treated this concept the same way. Sharing the history of the galaxy far, far away has multiple benefits. While the characters are learning about the events that brought things to the current point in time, so is the audience. It provides everyone with a frame of reference for the current landscape and lays out the stakes.
No scene does this better than Obi-Wan Kenobi's meeting with Luke Skywalker in A New Hope. The Jedi master explains that he fought in the Clone War alongside Luke's father and that the Jedi numbered in the thousands until his pupil, Darth Vader, betrayed them and helped form the Empire. This scene essentially lays the groundwork for Luke's story moving forward and Anakin's going backward, setting the stage for George Lucas' epic saga. With a similar situation at play in The Mandalorian, one of the series' creators explained that the same approach was taken to reveal the backstory of everyone's favorite baby...
In an interview with Vanity Fair, producer Dave Filoni said that Ahsoka's history made her the perfect character to reveal Grogu's backstory:
"I felt that if anyone would know or understand the Child’s history it would be Ahsoka. She has such a long history as well. By having her relate the story it also helps the viewer to understand some of her own backstory."
Filoni shared that the campfire sequence was meant to serve a similar role in The Mandalorian as Obi-Wan's discussion with Luke in A New Hope:
"This is similar to when Obi-Wan tells Luke about his father’s history. Through the story about Anakin, you are getting a look at Obi-Wan and his backstory as well. A lot of the campfire scene, as I call it, is shaped around that scene between Obi-Wan and Luke in A New Hope."
WHAT THIS MEANS
Din Djarin finds himself in a very similar position that Luke was in over a decade back in time. Unlike Luke, the history that Mando is learning about is sitting right in front of him, and for the first time, he's able to interact with someone who's able to communicate with Grogu. For Ahsoka, things are coming full-circle. The once-reckless padawan is now the master who points the hero in the right direction, and she provided all the information Din needed to understand the young creature he's come to care for.
Filoni expertly framed the campfire sequence in a way that was not only evocative of Obi-Wan's history lesson but also told much of the same story from Grogu's perspective. Mando is just as clueless about the Force as Luke once was, and the explanation Ahsoka gives about the mystical energy field is nearly the exact same thing Obi-Wan says to the letter.
This could've been cheesy, but it worked perfectly. Both Mando and the audience needed to know where the Child came from, and Ahsoka was the perfect person to relay that story and broaden Din's horizons. Filoni has stressed the importance of the teacher and student relationship many times, explaining how George Lucas wanted the heroes to develop. The role of the mentor is integral to every story told in the Star Wars universe, and Ahsoka can now play the role that Anakin and Obi-Wan once played for her.