I think the disconnect is it's more like a go-between for kbin/lemmy (a forum) and mastadon (a twitter/blogging service). They're both used to communicate subtly different things, and the same exact post comes across differently depending on what platform it originated from. Their tweets are displayed in our microblogs. Our forum posts look like tweets/twitter replies containing news articles to them. If you go to any pre-cloudflare magazine, m/gaming for instance, you can see a bunch of tweets "microblogs" from mastodon users doing the equivalent of farting around on their off-time, but they're all interpreted by kbin as posts.
Which is probably for the better. If each mastodon post were interpreted on kbin as individual articles, my whole feed would be clogged up with one user's 15-tweet rant about the hole in their socks or their mentally challenged sports team or whatever. But I do still get to read and respond to them, if they happen to tweet about something I'm interested in and one of my magazines picks it up. I could theoretically send tweets out the same way if I wanted to address that whole sphere directly for whatever reason.
I get the feeling the ability to do posts ourselves is probably more useful on the whole for someone who prefers personal blogging in addition to everything else. I don't know if I'll get much if any use out of it, myself -- I came for the forum experience. But I do have it if I want.