If you write correctly people will be more inclined to give consideration, if not credence, to your remarks. You may find that unfair, but that's the way it is.
Do people occasionally make typos? Of course. Do people occasionally leave out punctuation marks, or use them where they're not needed? Of course. Mistakes are unavoidable. However, educated people do their best to avoid mistakes.
Others with a greater accumulation of belligerent ignorance say, "I am how I am. Take me how you find me. You know what I meant so I don't have to do it right." Sometimes people know what you meant; to judge from remarks by others besides me in this thread, very often they don't. And even if they do understand you, because of your ignorant writing style they are often much more likely to dismiss your thoughts without further consideration.
It's your choice. It's a free country. Nobody says you have to write like you have had at least a basic education, but if you don't you may expect to be treated like a buffoon.