Earlier quoted context omitted.
This is total speculation, but my guess is that human reviewers of AI-written text (whether code or natural language) are more likely to think that the text with emoji check marks, or dart-targets, or whatever, are correct. (My understanding is that many of these models are fine-tuned using humans who manually review their outputs.) In other words, LLMs were inadvertently trained to seem correct, and a little message…
My guess is they were trained on other text from other contexts (e.g. ones where people actually use emojis naturally) and it transferred into the PR context, somehow. Or someone made a call that emoji-infested text is "friendlier" and tuned the model to be "friendlier."
(I once got that feedback from someone in management when writing a proposal...)