@Troy it's not so much about grammar; it' s about omissions or additions. With a garbled sentence like the one you posted, one is so busy figuring it out that the meaning can be missed. When i stumble over typos, or omitted or added words, what is written loses its impact because my mind is busy correcting what i'm reading or figuring out what was meant to be said.
Also, to me, these threads are posts that will be saved in the archives for others to browse through and read cold. Many are like articles in a magazine, the equivalent of essays or dissertations for people to read. i don't think of them as being "informal".
But i don't think this bothers anybody else. So, no "biggie".