I have to agree with the parent that on an intuitive level a single-sentence text message ending in a period conveys something pretty strongly. It does a couple things to me: indicating finality, turning an informal comment into a formalized sentence, and just feeling unnecessary thus prompting analysis. furthermore from a grammar perspective most messages are not proper sentences e.g. "yup" or "on my way". In the end we have to adapt our writing to the context, and texting has much more tonal analysis put on fewer symbols —