I have hired around 300 people for my company (currently employ 180 full time). I have found spelling and grammar and the ability to clearly express your ideas

I have hired around 300 people for my company (currently employ 180 full time). I have found spelling and grammar and the ability to clearly express your ideas in writing to be probably the biggest indicator of intelligence. People who are not good writers generally turn out to be not good employees either. I agree with the article that you need to make an exception for people with English as a second language for spelling and grammar... but you should not make that exception for the clear expression of ideas.