Well I am a teacher and I would support most of what Iggy said about the need for clear,well spelt,grammatically correct and hopefully well punctuated written,typed or spoken english, although I would perhaps, have put it more diplomatically.
If you want to communicate information to another you do need to apply all of the above.If you don't then you are in danger of causing confusion and with passing on technical info to a rube like me you do need to leave out the technical jargon and the acronyms.If you are too lazy to do so then all you do is make me pass over what maybe excellent advice because I cannot be bothered to try and decipher what you have typed.
You also in speaking need to leave out idiomatic english IF you want to communicate to another who doesn't speak that particular idiom.It also helps to leave out the patois as well.Rapping is all well and good in the right place but frankly it baffles me.