Several people at my work do use LLMs for this in code, commit messages, and even on Slack. It may not be everyone or even a majority but it is something that some people legitimately do.

While many here are saying "who cares about your spelling and grammar," they have not been the people whose poor English gets them flagged as being somehow less intelligent or credible. Half the problem with LLMs is that they speak eloquently and we use that as a signal of someone's intelligence and trustworthiness. For someone who is otherwise intelligent but doesn't know English well this can be a major setback.