In Devarim 11:2-9, Moshe tells the Jews that he’s not speaking with the generation who didn’t see what Hashem did to Mitzrayim… and many other miracles. Rather, he’s talking to those who saw these events with their own eyes.
This episode deals with the significance of this point. After all, who cares if they saw it with their own eyes or if they knew it from their parents’ eyewitness testimony (as we know it)?