No I think you're missing the grandparent's point. Inflection in spoken language "translates" to facial expression in sign language.
For example, if we ask a question, it's not just that our voice goes up at the end. Our eyes move in a certain way too, slightly more opened and our eyebrows and sometimes cheeks raise.
And nobody's at a distance, the cameras are always on either a medium or close-up shot when filming politicians speaking.
If subtitles were equal value or even “good enough”, they’d be used exclusively. That they aren’t should tell you something, and you repeatedly protesting that you are unable to comprehend the value doesn’t mean it isn’t there.
Separately, relatively dry sarcasm can't be visually picked up directly, but a signer may be able to suggest some of that with body/hand language.
I don't know how you'd possibly attempt to objectively quantify that degree, but my guess is that you're understating it. The entire deaf community is probably not mistaken about which means of communication are the most effective for them.