I don't know much about EOS, but vote buying/selling when it comes to block producers and upvotes are two separate subjects.

In my opinion, Steem is semi-decentralized. While votes for block producers can be seen as a political instrument that can decide the course of the blockchain, upvotes, delegations, and actions that affect the reward pool distribution carry economic aspects of the blockchain.

Theoretically, a single largest stakeholder or few top stakeholders can determine who the top block producers will be, and blockchain can be completely centralized. Is that good or bad thing? I don't know. But I believe, such possibility may keep larger outside investors away. At the same time, other investors may be interested in more centralized blockchains.

When I first learned about Steem, my simple assumption of economic incentives would be that larger stakeholders would be more interested in longer term increase of value of their holdings, rather than short term gains from reward pool. With that they would/could empower smaller to medium stakeholders to accelerate the growth of the platform in social media space, empower developers to create new apps, etc. Win-win scenario for everybody, everybody would grow as a community. However, I came to realize that was a naive thinking. Reality of the the dpos economics seems to be much more complex than that.

But I wouldn't call it broken. I works, just needs some improvements, which is just part of the process.