While rep is gamable, delivered just like financial rewards and can be bought, it is far less fungible, as it isn't tranferrable as is Steem or SBD. That means hordes of bots won't have the rep to Sybil attack the witnesses with if witness votes are based on rep-weighted votes--unlike the current system which requires only money to control the platform.
While the DPOS idea is sound as far as you take it in the above comment, clearly ROI based on circlejerks, delegation, and bots severely compromises it's ability to influence whales to act so as to benefit the platform as a whole.
The trending page is a view into how DPOS is encouraging good content. A better view is to examine how Steem is increasingly concentrated in accounts that have more of it.
DPOS is the best way to encourage profiteering, not content creation.
Too bad I can't resteem a comment.