Am I posting comments in every single known language? No.
Okay then, that leaves us with my point being, that just because someone hails from another country and comes to a forum where English is the dominant language and makes grammar mistakes, they should be pardoned from the whole idea. By correcting someone, they will realize how and why they were in the wrong grammatically. Thus they learn more, "Ah, what a silly mistake/Dang, didn't know that!"
It's not wrong to be wrong, it's enlightening.