I don't think people's literacy skills should be used as a form of elitism, or to humiliate or disparage. And I don't think there are many who get worked up about the occasional spelling mistake in an otherwise coherent post.Not everybody has had the chance to have been educated well. Not everybody who has had an education has done well at it. Not everybody speaks English as their first language.
It may be that some people are lazy. But it may also be that people have difficulty with the written language.
But there are a significant number of posts where people do appear simply to be lazy. If you know that you're not good at spelling, then you can use a spell checker. Surely anybody who's capable of getting onto the forum has the requisite skills to identify a long sentence or paragraph, and insert some commas and paragraph breaks. If you're making quite a few points, it's not hard to number them, or use bullet points, even with poor literacy skills.
If you are asking others to provide their time and expertise - for free - to assist you in solving a problem, it seems both self-interested and courteous to ensure that you state your problem clearly and that it's readable.
People with genuine literacy issues have my utmost admiration for their ability to function despite the continual frustration of living in a world awash with words. I'm sure that if I had to get by in a world which constantly required use of a skill that I lack, such as having to follow a gym class teacher's instructions , I know that I'd find life extremely difficult and frustrating, and quite possibly "go postal".
I confess that I'm assuming that those people who are unlucky enough to have significant literacy issues are unlikely to try and solve their problems by posting on Somersoft; I assume they'd prefer to ask a friend, or phone the RTA or a legal advice line. But I'm admittedly ignorant about the coping skills of people who struggle with literacy, and quite happy to be corrected and enlightened.