I am particularly drawn to professionals that write elegantly well. Maybe it is something about the underlying assumption that only professional writers are expected to know how to write, and write really, really well.
Something about reading a pro footballer who writes elegant prose in a fluent style. Or a software engineer who writes about their life in a style that does not betray their professional proclivity.
Perhaps I hold these assumptions because I believe to be good at anything, you need to first be devoted to considerable practice and iterations. Problem is, I do not expect that professionals in fields other than writing are able to devote themselves to the practice of writing, much like writers; hence, should not be expected to be even close to, or above average.
But every once in a while, I (pleasantly) learn how mistaken I am. I come across a brilliant person committed to their (non-writing) profession, who also possess a strong penchant for writing. Paul Graham is an excellent example of this. James Currier of NFX, too. Morgan Housel as well.
I also think that this assumption stems from my belief that most people tend to be one-track, incurious specialists. Sometimes we see this with certain groups like doctors. Though incredibly brilliant and useful, more often than not, tend to be oblivious of even the smallest things outside their domain.
Interestingly, you find that engineers typically are the opposite. They usually possess a curiosity that actively finds them tinkering with the world around them. Thereby making for a busy mind ladened with the sheer weight of observations, questions and ideas needing to be unburdened. Writing happens to be one of the finest mediums for lossless* unburdening.
To conserve the integrity of their thoughts, they must be fluid and adept with the tool of unburdening, consequently making them better writers by necessity.
One might argue that engineers are good enough writers because a significant aspect of their profession involves writing —specifications, documentations, descriptions etc. Which is correct. However, the basis of excellent writing I am concerned with is not of the technical form, but the simple, pleasant, concise form, shorn of jargons and technical taint.
When a financial analyst writes, a layman might struggle to grasp the meaning. When a doctor writes, the same applies. Basically, when a professional in any field that uses writing as an integral part of its standards, writes, it is almost useless to those completely outside that field; as far as comprehension goes.
To distill thoughts and ideas in as simple a way as possible is a mark (expectedly) of a professional writer.
*sometimes data needs to be repackaged in a format that allows for easier, faster transmission and distribution. It might involve compressing to a smaller file size (like music or image) using certain techniques (like downsampling) that reduce the file size and significantly loses the original quality permanently.