While true, no one needs to be formal here. I'm more worried about them getting the point across, rather than whether their grammar is correct.
I'm not concerned about formality at all. I am concerned about reasonably correct grammar--the entire idea of grammar in the first place is to get your point across! Misplaced commas, incorrect words and so on can significantly change what you meant to say, or at least make it harder to figure out. ("Eats, Shoots & Leaves", yes?
--Eric