I agree, however I realize that "texting" is faster and more convenient when done in a short sentences and words. I've learned a lot of that from my kids. There's a time and place for it and messaging on your phone seems to be the time and place...not when you are writing an essay or answering test questions or filling out a job application.
It isn't or shouldn't be used as a general manner of writing. If this "professor" believes that, he shouldn't be teaching. The world is not your smartphone.
Agreed on that!