In reality, for most writing is a fading interest. It's a skill that anyone can really pick up if they wanted to but doing so is easy to learn and hard to master. You can go long periods of time writing and never improve.

Due to how the system as whole is designed most writers never improve. It's just how it works in the end because of the lack of a coherent structure or guidance system. Only if you belong to pre-established writing groups will you even really have a chance at learning it.

Sure there are several references openly available online, but all it can teach you is syntax. What you need to be a good writer is experience, training and mentoring which most people will never gain the opportunity of having. And even to those that do, it's a lifelong endeavor and one that requires complex knowledge in a variety of fields. It's one that most that pick it up will never be able to comprehend themselves or when they do, it's too late and trying to do so is fundamentally impossible for them due to their situation.