I always have subtitles on in games. Especially since I find it hard to focus on the words being spoken and video game cutscenes are almost always unable to be rewound. During gameplay it's harder to read and play at the same time though, although over the years it's gotten easier.

Through my years of watching Anime it's also quite easy for me to watch and read at the same time.

I think for watching movies they can be useful too, because it feels like almost every movie coming out now has terrible audio mixing for the average person. Even the audio mixing in a Dolby Atmos theatre doesn't seem right. If you watch any modern film mastered in Dobly Atmos on a TV with a sound bar you will have a bad time. You'll have a worse time if you're watching with just the TV speakers.