In fairness, not all people can write well.
However, the higher one goes in a firm, the better one's communication skills
should be. Both verbally and in a written form.
So, no saying "can't" instead of "cannot" in a report. No using "which" without a comma. And use "that" as a restrictive term.
Oh, and use a semi-colon to link two grammatically correct sentences that have the same point and subject.