Edit: I'm asking because I suspect your answer is going to be "it doesn't/that's not the point/who cares?" But people who read blogs will just flock to the centralized services that solve curation & search quite effectively and keep users reading. And then this centralized service will have strong incentives to become _more_ centralized, not less, and decentralized solutions like this one never really gain traction and become functionally irrelevant.
I don't think that's true. People read blogs by writers they like (they go directly to that writer) , or about topics that interest them (they follow links from a website or social account about that topic) , or because they're looking for a specific post about a specific thing (eg they Googled). None of those things are best served by gathering writers on a single centralised platform. In fact, so long as blog posts are open the reader probably doesn't care how the posts are published. (Side note: this is the flaw in Medium. No one want the subscribe to the Netflix of blogs. People might pay to access their favourite writer, but not in the long term.)
Centralized blog platforms serve the writer. They're easy, they often have good tools, and they have an audience, although I doubt that's actually very useful to most writers - just having more readers without caring who they are is pure vanity. You want relevant interested readers if your blog is going to be effective promotion for you.
Ultimately, blog platforms are fine. Writers are a great customer base to have. Just don't kid yourself blog platforms benefit readers. They don't.