There's a whole article here from the BBC site about subtitles in films. It is quite interesting to read because it is nothing to do with deaf people, it is about hearing people using subtitles to help them to understand foreign languages or thick accents. A Mexican film producer is upset because his film was released with subtitles to clarify people's unusual speech. He does not want that.
Here, ladies and gents is what the hearings really think about subtitling. And in this entire article there's not ONE word about deaf people or their needs.www.bbc.co.uk/.../world-46822379
It's not much different from BSL output objecting to subtitling when often its the ONLY way to understand what on earth they are saying. Given the nature of sign language, it is impossible to use any lip-reading ability too. In the UK regional accents can be an issue without subtitling deaf nor hearing would follow some of them! You thank the gods text exists.