The way the curation system works now
The voting system is in place to reward quality content. By voting you essentially bump up a post in the rankings, and credit the author a reward. As a curator you earn more rewards by voting early on content that will become popular.
The effect of this curation system
Because the most rewards are gained from voting on posts you think others will vote for too, content with potential popularity is favored over quality. So posts people think are going to be popular are rewarded the most. This will result in relatively low quality posts dominating the front pages, overshadowing great blogposts. The goal for steemit should be to provide quality content, and not to be a popularity contest like conventional social media.