I find myself on both sides of this argument.
For five years in the mid-80s I produced what was still called an “underground comic”. Misspellings, ravings and grammatical errors were part of the persona I adopted as "editor". Regular readers - ultimately around 700 hardy souls - “got the joke” and were part of “my” community. I see a similar thing happening with blogs - just as it happened in the pamphlets of the 17th century . To be perfectly honest, none of these lads begin to approach Abiezer Coppe in foul-mouthed vitriol and sublime incoherence.
Yet I do see a problem. The origin of English is unlike that of any other major language. It is essentially a fusion of two wildly incompatible tongues - Anglo-Saxon and Norman-French - with contradictory grammatical structures and unrelated vocabularies. Their synthesis created a new language of incredible flexibility and inclusiveness. No word is foreign to any English speaker.
This in turn creates a difficulty, one which was faced by the earliest writers, particularly after the invention of printing. Given an immense vocabulary, if people are going to communicate effectively they need to have certain things in common. That is the origin of grammar and agreed spelling. I love the English literature of the “early modern era” - say 1480 to 1600. It was an age of social and intellectual transformation, with astonishing discoveries and ideas, spread by new, democratic, communications technology. People wanted to share thoughts and experiences. They developed a new sense of themselves. Very quickly, during this period, written English moved from a web of incomprehensible local dialects to a common, universal language, not because it was "right" but because it made communication easier.
Slang or dialect is perfect in its natural place, but wider use runs counter to the fundamental nature of English as an inclusive language, as its purpose is to exclude others. That is why I believe it evokes hostility amongst people here. A simple misspelling is no fault at all, but to deliberately misspell is an egotistical adolescent affectation. I knw. I did it too. I still sometimes do, in letters to old friends, as a tacit acknowledgement of shared intimacy and experience.
But - to use such an approach in a context like this forum, where people from many countries and linguistic backgrounds are trying to share knowledge, experience and goodwill, can easily seem to suggest that the user does not really wish to communicate and disrespects the community.
Just my two groats worth.
Ian