They fear of being judge by other that is why they don't collaborate on comment area. In fact, grammar don't matter as well as the spelling, as long as you express your though and the receiver can understand it, it's acceptable. So, most of them don't react on the website.

Based on my experience as a blogger and a reader, what impresses your visitor are, the layout, the images, and lastly the content of your website. If they find if valuable then they feel impress. Otherwise, don't.