Thank you for sharing this important counterpoint to the prevalent perspective. While not everyone agrees with the downvoting for this reason, it is important to remember a few things:

1. Both upvotes and downvotes (flags) are built into the protocol for specific reasons. These reasons are not secret, but are fully explained in the whitepaper.
2. Upvotes earn curation rewards, while downvotes do not. This unbalanced schema is specifically intended to create an ecosystem where positive feedback is much more prevalent than negative feedback, because there are significant costs to negative feedback.
3. The value of your upvotes and downvotes is directly proportional to your investment in the ecosystem. While there may be disagreements about whether people have short-term or long-term perspective on how they use their votes, you have to be invested for at least 13 weeks (or gain the trust/support of somebody else who is) for your votes to have any value. Theoretically, this encourages investors to make choices with their votes that will improve the long-term potential of Steem.
4. While you may disagree with the way others use their votes, they have earned the right to vote however they want, either by virtue of buying into the system or from previous earnings.

Now I realize that people may take issue with any of these points, but the incentives are carefully structured. I would hope that people disagreeing with the outcomes will think about how the incentives lead to specific outcomes and how they can use their own SP to improve the ecosystem, instead of knee-jerk reactions and complaining.

I have seen many posts complaining about spam, with spam in the comments to that post that don't have downvotes from the post authors. If you hate spam, downvote it. If you reward spam (or ignore it) there will be more of it.