On my alma mater's BBS, where I still keep in touch with old friends from college, an apparently new student posted a comment where s/you/u/g and questions didn't end in question marks, etc., and it was generally difficult to read.
I noted that if she had a point, it wasn't getting through, because reading her post gave me a headache, and I couldn't bear to get through it. I wrongly suspected the person might realize from this that communication is a two-way street, that to be understood, you need to be understandable.
She responded that I was overreacting, that there was nothing wrong with how she was writing. I tried to express the idea that most people won't bother to read her posts if she continued, and that they will mostly think of her as a careless, illiterate, sloppy person.
For this, some chastised me, saying all people make language errors, and we shouldn't judge people based on their cultural writing styles.
Flummery! I won't apologize for forming my impressions of people by how they present themselves. Why this is a difficult concept for people to grasp, I do not know.