If I need to watch quietly or if the audio is simply hard to understand for whatever reason, sure. There are reasons, they have their use cases. Obviously it makes sense for those that are hearing impaired or when the content is not in their primary language and they need the help. Sometimes it is a necessity.
But otherwise if you have them turned on without a specific need, you're distracting yourself from the frame, reading dialogue before it happens, spoiling the timing and delivery, missing visual subtlety or outright missing the frame altogether, encouraging a lack of attention and overall lessening your own experience. (Obviously that's talking with new content in mind, not something you've already seen)
A lot of people turn them on because they listen to content using a TV's built-in potatoes and to you I say please at least get a sound bar for your primary viewing device. Even cheap ones are better than the built-ins. A lot of media accused of poor mixing is in reality you trying to play sound out of a vegetable.
It makes more sense for games because the mix is dynamic and can often get drowned out by whatever is happening. And because you're actively playing rather than passively watching, it can be harder to give the dialogue your full attention. If given the option in settings, I usually turn dialogue volume up and the rest slightly down to try and combat that. However sometimes depending on the game they will need to be on.
I pretty much assume that anyone voting for "always" without a specific reason like hearing or language or baby or whatever is the type of person who cant sit through a movie without checking their instagram
I think the poll would be more informative if given options "always just because" and "always because reasons" in addition to the others