It's not your hearing, it's the mix. Source: I'm a mastering engineer with a monitoring setup worth six figures and I use closed captions too.
Speakers in TVs used to be tailored to making speech intelligible. Nowadays it's... well whatever it is, it's not really meant to do anything. Not even the more high-end popular speaker systems are meant to do anything at all, really. They all just kinda sorta make whatever is coming out of them sound flashy and whooshy. That's another reason why movies are even more difficult to understand.
And let's be honest - a lot of it nowadays is just not _worth_ hearing... Staple tv shows form the 70s that fell into obscurity for being extremely pedestrian had better writing than nearly all big-budget movies nowadays. I remember when Pig came out recently, it was the only good movie during a span of maybe 3 months. That's how dire it is nowadays.
Edit: oh, and I forgot about the ubiquitous 5.1-to-stereo downmixing bug: https://news.ycombinator.com/item?id=32883588