I like how people use the 'I can do what I want on the Internet' excuse. You're still interacting with real people. How you type is how you convey yourself. Do most people tend to walk around in dirty clothes, un-bathed, hair a mess, stinky like shit, and acting like a complete retard in public? No. So why the hell do most people find it acceptable to do it on the internet?
How about this, we'll stop correcting your grammar, but in turn we get to treat you like you have multiple and severe mental retardations, and disregard EVERYTHING you have to say instead?