On the internet only 2 types of people correct others. Smug people and the ones who can't think of a good argument/Counterargument so they resort to correcting grammar.
The people who actually want to help you by correcting your grammar aren't that many.
I honestly dislike people who correct my grammar (or English, in general) openly, unless that person is my mentor or something.
English isn't my first language, but you know... Correcting people right out in the open can be really awkward. There's also little formality on the internet anyway.