Grammar may seem tedious and frivolous to many. You may think you’re wording is right, but then you ended your sentence in a preposition. Or you split an infinitive. Or you used ‘affect’ as a noun. Just when you think you can get away with a passive sentence, you’re suddenly overcome with the fear of the wrath of your anthropology professor who definitely reads her copy of the Chicago Manual of Style to her kids every night before bedtime.
You ask, what’s the point? Why do we need such strict rules to communicate an idea?
Because it’s important to maintain a consistent structure so that we can most effectively understand each other. It’s a sort of framework we need, a basic element, which we can build from to explain our ideas with as little confusion as possible.
Grammar is like what Arthur Shopenhauer says about mankind… and porcupines:
A number of porcupines huddled together for warmth on a cold day in winter; but, as they began to prick one another with their quills, they were obliged to disperse. However the cold drove them together again, when just the same thing happened. At last, after many turns of huddling and dispersing, they discovered that they would be best off by remaining at a little distance from one another. In the same way the need of society drives the human porcupines together, only to be mutually repelled by the many prickly and disagreeable qualities of their nature. The moderate distance which they at last discover to be the only tolerable condition of intercourse, is the code of politeness and fine manners; and those who transgress it are roughly told–in the English phrase–to keep their distance. By this arrangement the mutual need of warmth is only very moderately satisfied; but then people do not get pricked. A man who has some heat in himself prefers to remain outside, where he will neither prick other people nor get pricked himself.
He explains that humans maintain a basic set of manners so that we can tolerate as many people as possible based off this minimal foundation that we’ve all agreed was an acceptable way to act. Like politeness, grammar is also this minimal foundation to which we must adhere for others to understand and make communication possible. Simply put, we rely on grammar, whether or not we’re cognizant of it, to interact with others on a basic, often misunderstood level.