Obviously it’s important what you write about because if there’s no content, no one will bother to read it no matter how brilliantly you write. On the other hand, it doesn’t matter what you are writing about if you don’t have the ability to write it in such a way that someone can make sense of it. You can’t separate these two things. You need something to say and the ability to say it coherently. Writing isn’t a collection of parts. It’s a talent, a gift wherein you can take words and form them into cogent, interesting, or even enlightening and/or entertaining collections of words, also known as sentences, paragraphs. or (gasp) books. One of the most irritating things about social media is that it has made everyone believe they can write. Being able to drop words onto a writing surface doesn’t mean you’ve said anything.
A writer who has something to say needs to use sentences and real words — not social medial abbreviations like LOL, OMG, WTF, BRB, et al — OR emojis, which is the new equivalent of hieroglyphics. Writing should enable anyone of any age to get the point without mental strain. They might not agree with you. That’s an entirely different subject, but they will at least understand what you are trying to say. In some cases, your writing might shine a light on an idea or a new item of information, or even a story and characters! Did you know that people can learn by reading? It’s true!
That’s what we call “writing.”