I'm new here. My blog was new too, had only two posts there before registering here. I asked myself exactly the same question first days here! Then my second post, instead of linking to my blog i reposted here. So again I asked myself, should I stop with the blog and just write on Hashnode?
That's why I really like the concept of Hashnode. It's a kind of hybrid. Has a bit of StackOverflow, a bit of blogging, a bit of Reddit linking and all wrapped in a community that's feels homy and personal. That's exactly why I think this is better place to Blog. At least for starters and smaller blogs. Right away you have public, community. Your blog without this arround requires more marketing work.
However, for professional blog writers, if you maybe make a living out of that and don't just have a need to share some thoughts... I guess you want full ownership of back end, domain, advertising, etc.