There is a good book about the evolution of written communication as the Internet evolved. "Because Internet" by Gretchen McCulloch goes into some of the subtle implications of using punctuation such as periods ending sentences, capitalization, etc. Text makes it difficult to convey emotions and subtlety so even using punctuation can add signal to the communication channel. It turns out there is relatively powerful tonal communication through those deviations on "standard" English grammar rules. Similarly, Emoji also acts as a replacement for gesturing.

Very interesting book and worth reading to understand how to tailor communication for the medium.