A lot of people are adequate writers, but the number of people who are able to write really well seems to be an ever shrinking number. Most people don’t really have a comprehensive writing education any, whereby they are taught how to formulate their writing so that it reads well and means what it intends to mean; many people just sort of muddle through writing.
In order to become one of those few people who has objectively great writing skills, you first need to understand what that constitutes. Writing is intended to convey meaning to the reader, and this is by no means a simple process. After all, different people will react to different stimuli, which in the practice of writing means that you can never be sure that what works for one person will definitely work for the next. Great writers tend to be able to understand the psychology of their readers and respond accordingly, usually by changing the tone and flow of the words they’re using.
Great writers are, of course, articulate in their writing, but what sets them apart from the majority of good writers is that they’re able to easily adapt their writing style to what the situation and environment requires. This is important in the business world, as depending upon whether you’re writing for B2B or B2C, or even internal communication, the style of writing can impact their understanding of what you’re trying to convey to them and how positively they interpret it.