xkcd #2942: Fluid Speech
Alt text:
Thank you to linguist Gretchen McCulloch for teaching me about phonetic assimilation, and for teaching me that if you stand around in public reading texts from a linguist and murmuring example phrases to yourself, people will eventually ask if you're okay.
That is absolutely correct. Writing isn't language, in fact. Language is instinctual and barring severe brain damage, everybody on planet Earth learns to communicate in at least once. (Sign languages are language. Indeed they're an extension of body language.)
Writing is an attempted encoding of language (and not a very good one, given how much is lost in written form vs. in-person communication!) and is a skill that takes a lot of time and effort to learn. Writing is not instinctual in the slightest.