"There is plenty of material that all of us agree doesn't deserve rewards."
No, there isn't. The world is a vaster place than our minds can encompass, and even spam is considered, by someone, worthy of an upvote.
Otherwise, no one would post it.
Overall, however, you are right. No one, no matter how high their rep, or how fat their wallet, has a right to tell anyone else what to value, or whether to upvote it.
Either Steemit eventually conforms to this factual reality, or it gets replaced by platform(s) that do.
Invest accordingly. The real world cometh.
You're right. That sentence should read "that can reasonably considered unworthy of reward of any kind."