If you want to style your WordPress to look like Medium, watch this video. I use Visual Inspector to look at the properties of elements on the target website, and style WordPress with CSS using the Genesis theme.
Why is it worth maintaining your own website as a writer? Because it's simple and necessary to be digitally independent and knowledgeable, so that you can hone your skill and craft.
Everything digital is an input through the keyboard and mouse, and doing it yourself is personally empowering.