Because the speaker is the one selecting the verbal data, which is not the most copious portion of face-to-face communication, but is the most precise form of it.
You provided a great example by choosing to include a symbol that more clearly conveyed your intended inflection, even though it didn’t seem necessary to you, because you weren’t sure it wouldn’t be necessary to me. That’s an excellent use of the speaker’s position to communicate clearly.
Because the speaker is the one selecting the verbal data, which is not the most copious portion of face-to-face communication, but is the most precise form of it.
You provided a great example by choosing to include a symbol that more clearly conveyed your intended inflection, even though it didn’t seem necessary to you, because you weren’t sure it wouldn’t be necessary to me. That’s an excellent use of the speaker’s position to communicate clearly.