> If your job is to write text that is then published, i.e. intended to be read by a large audience, then your spelling and grammar should be good, or you'll be judged by it.
the problem is that even if you are not being formally published, you are going to be writing things intended for a reasonably wide audience, even if that audience is just your company management as you try to convince them to do something.
If you are not in a job where this matters, you are not in a job where your grades matter at all.