I gave it a go but I don't really get it. It just seems like a reduced version of Steemit that posts to your feed anyway.
If you could hide the posts from Steemit so they were only visible to other zappl users then it would make sense.
Unless I'm missing something?
What you're describing in the second paragraph will probably happen eventually - right now steemit includes EVERYTHING and I agree that it is annoying.
Zappl has a lot of growing to do - but I think if it is able to improve over time like DTube has, it could become an eventual legitimate competitor to Twitter.
If not, no harm no foul basically - either way I'll be microblogging somewhere :-p