No actually RKM is NOT wrong... you are. When hiring someone, you are hiring them to represent your company, both orally and by written word. If I wrote emails or other correspondence to our clients littered with bad grammar and misuse of words such as "their" for "there" I would be fired. Likewise if I walked into a client's office and greeted them with "wat up dawg" I would be fired! Everyone makes typos on occasion, but continuously making the same mistake over and over tells your employer you either don't know the correct usage or are just too lazy to proof-read; either way, not good in an employers eyes.
I work in a professional environment and it is just not acceptable to be illiterate, either orally or in written form.
It's not "shit like that keeping people down" either. How you present yourself is how you will be perceived. The world does not
owe anyone anything. If one wants to speak and write like a moron then fine... they will likely work in low-wage jobs where the employer can't be as picky.
Everyone has a choice to make, but the business world isn't going to be tolerant of people with poor verbal and written skills.