I similarly struggle to understand what actors are saying when they’re backed by theme music or other physical things going on as part of (or behind) the story. Captions help me actually consume video rather than feel lost in it. Without text I pretty much would stop consuming video entirely.
Granted, I’m 40 so I can’t speak for the youngs. And I hear just fine in that the sounds are all present in my ears and my brain. They just get jumbled and being able to catch up with text helps immensely.