This!! Most speakers/soundbars suck, and if you don't have a center channel in your sound system, voices will wash out with the background noise/music since the speaker (as in person speaking) is usually the focus of the shot and mostly audible in the center channel.

There's supposed to be sound engineers on every show/movie to make sure it sounds good but the gap lies between your audio system and the reference systems they use. A good analogy is the infamous Game of Thrones battle that was too dark. They edited that episode on reference grade monitors where you could see what was happening, but the average lower end tv and viewing environment couldn't translate the same black levels and details that the editor's had seen when they worked those scenes (they were also intemtionally edited to look dark and chaotic on the reference grade monitors*, which added to the problem)

That being said I still use cc with a lot of content. I think it would be less prevalent though if it were not for the gaping holes in most audio setups.

This is one (of many to be fair) reasons I quite dislike the theater. Others being "free" food/drinks, my dog, my comfortable couch, pausing, and my bathroom. I've wondered before if they could give people special glasses (a la 3D glasses) that would show the "hidden" subtitles at the bottom. But even that wouldn't get me back in a theater.

Don’t most cinemas have a personal screen with captions available on request?

Maybe I need to improve ours!

I have zero problem at movies. But I always watch TV with subcaptions. There’s usually some words that I miss

Personally, I've never had a problem hearing dialog at the movies. The volume is far too cranked up to miss it.