Thanks for your comment! I think we have to distinguish between the steem blockchain and the interfaces/apps like steemit/busy/... like you say.
The blockchain enables all kind of content, and I agree to your points that it can do all that. That's what zappl/steepshot/dtube/utopian and others are doing right now. One might argue if a 75%/25% share of author/curator reward is appropriate for each type, but in principle this can all be handled with the same blockchain.
For the interfaces/apps the vast majority of posts currently come from steemit.com, the share from other apps is rather small (see my previous post if you're interested in numbers). I myself also mainly use steemit. On steemit all post types are (mostly) shown in the same way. I'm following a few hundred accounts that publish in a blog-like manner maybe once a day, mostly more infrequently. With high frequency news/link posts in between I simply would miss blog posts. That's the reason I'm currently not using steemit for news/links. This could indeed be handled with a separate app, but then the steemit feed becomes pretty crowded. I think steemit at some point has to adjust to different content types, maybe something like separate home feeds for different apps or categories, to remain usable as a generic steem interface.