As a reader, I usually don’t care who wrote the post I’m reading. I also don’t care about seeing more content from the same person, which is all I would get on a personal blog; in fact, I would prefer to see related content but different viewpoints from other people, which is what Medium shows me. I want to read them all in the same format, not hop between different blog layouts. I want them all to have consistent like/comment mechanics. As a reader, sorry, I just don’t care about your personal brand or platform. I want to easily read a lot of stuff by different people on a topic.
Never used it as a writer, but why should individuals have to set up their own SEO, comment system, blog system, etc just to post an article? Because they think that they’re so important or controversial that they need a personal space/brand? For most writers I think you get a lot for free with Medium.