The main advantages of Medium are no muss, no fuss posting (or article management), getting paid, and network effects of an audience that wants to read things. And the hosting is free. So for some it can be compelling. But the paywall has reduced overall viewability. (I don’t know what income is like or how it’s been affected.)
I don’t want to manage the security of my own blog, having to manage updates of plugins so that my site doesn’t get compromised by old software when vulnerabilities are found. And I don’t need specialized Wordpress plugins that one can add to one’s own hosted site. For that reason I prefer to have my blogs hosted by Wordpress itself on the wordpress.com domain. Prices for a blog start at free with dozens of themes to choose from, however they add ads to the blogs, and you don’t have access to sophisticated plugins. But Wordpress maintains the blog, does all necessary upkeep and backup, there’s a good iOS app (or you can post from IA Writer or Ulysses and other apps). Pay tiers offer additional features.
If you like those Medium network effects nothing stops you from having a blog under your control, with all your posts duplicated on Medium.