Writing style can be used not only as a confirmation where you suspect some one, but if say you have a large pool of people, and you want to narrow down to a most likely candidate list for further, closer examination.
There is really sophisticated software that is used, by the NSA, CIA and FBI - the usual suspects, but also social media companies. It one way they ID people who have different accounts aand its also one of the tools used to uncover the Russian/Chinese/NSA/Macedonian hackers.
Style can include spelling (US vs UK vs AUS vs Continental) but it usually focuses on the number of certain words (articles, negations), the reading age (elementary vs High School vs College) and, favorite words, repeated phrases, that a person uses (ideolect -
https://en.wikipedia.org/wiki/Idiolect) but also that they use because of their profession - lawyers write in a different style to doctors, say. And syntax. People organize thoughts in specific ways and this is more or less indicative. I once worked with a man who quite literally produced writing like silk. It just flowed. I saw him composing documents, where he would just dictate it to someone to type. Fucking amazing. And you read it and believed it. His colleagues hated this talent. But any document that had been near him you could tell; it had his finger prints all over it. That's what made me look into it.
So, the trick is to limit online posts, and limit length of posts. And strip all identifying data from posts, photos etc - screensnip is useful here, plant false leads, and use a VPN, and linux.