I’m not sure if it’s a plot device or just lazy character development, but I hate expository dialogue unless it’s done right. Which is kinda rare in my experience.
A: “Are you going to the town Christmas festival?”
B: “Town Christmas festival? What’s that?”
A: “Oh, it’s a gathering in the middle of town where (blah blah blah). We used to go every year before Mom died in the accident right before I went off to college, which served as motivation for me to attend medical school and become a trauma surgeon.”