I think the issue of plagiarism and discouraging it has a lot to do with the fact that you can be paid for your content. You can share links and other info without plagiarizing. In fact, that actually happens a lot.

Link sharing is not plagiarism. Claiming that you created content that was actually created by someone else is the issue. With a limited rewards pool, stakeholders have put emphasis on original content and prefer to simply not reward plagiarists. That doesn't mean that such people cannot post/share...it only means that they usually won't be rewarded and probably won't have much of a reputation score.

That being said - this was designed as a blogging platform. There will be other interfaces that won't have an emphasis on long-form blog posts. The STEEM blockchain is not Steemit.com.