There's a couple reasons why I use subtitles all time. Firstly I'm getting older and can't hear as well with background noise. If my wife is banging around in the kitchen I can't hear dialog from the TV. With subtitles on I don't have to mess with the volume.

Another issue is media producers (TV and film) have this idea they need to blast you out of your chair with sound effects and music. So if you turn up the volume enough to hear the dialog clearly, you're going to get blasted by everything else. Trying to manage that with the volume control is damn near impossible. Interestingly I've noticed "dialog boost" appear on occasion in sound track options from my streaming provider. I use it when the option is there. That kind of indicates a global problem.

An issue related to sound leveling is actors used to come out of theater where they learned to annunciate loudly and clearly. It seems actors don't get proper stage training anymore and now it's okay to mumble and fail to annunciate. A decent director should never allow that.