Whenever someone mentions grammar, there is a tendency for eyes to glaze over. Or, equally likely, a general hostility on the basis of perceived imminent snobbery. Which is interesting, as there are few things in the world that are equally likely to cause indifference and hostility - this in and of itself tells us something.
It does not however go without saying. That would be the opposite of grammar.
Grammar never goes without saying. It is the saying.
The most common way to think about grammar is to think about rules, rules and more rules. A comprehensive set of rules that are imposed willy-nilly on you, mostly in an educational setting, where you are more often than not found to be in the wrong. Wrong in the sense of a red marker pointing out just how unruly you are, in an unequivocal display of the relationship between ruler and ruled.
This is what the education system drills into its pupils. It is also, quite ironically, wrong.
Grammar is not a system of rules. It is an applied skill, a mastery, a competence. A call to action, an agency. A way of navigating the world.
The art of knowing how to string words together in a way that makes social sense. When it makes social sense. Even and especially when the rules of formal grammar are broken.
Maybe it is better to say it in a slogan. The most brute force of all the grammatical maneuvers:
Grammar is a gateway drug to poetry.
Something else that doesn't go without saying.