This is spot on. As a baby, you typically have two affectionate caretakers who dedicate a significant amount of their time to teaching you language/words, and also shower you with love/praise/attention for every little bit of incremental progress. Also, you're in an immersion program: you often can't communicate your wants/needs until you've learned the language, which adds another layer of incentive.

As an adult, if you were sent to an immersion program in a foreign country with two full-time foreign tutors/caretakers who loved you, like legitimately loved you with all their hearts, you would pick up that new language pretty darn quick.