I don't agree that Steem voting rewards should be linear. All upvotes on other accounts' posts would come at the theoretical cost of not upvoting your own comments. Effectively it would turn it into a convoluted tipping game. The other similar blockchain social projects are essentially tipping platforms and I think Steem holds an advantage over them because the rewards are superlinear thus encouraging more natural voting.
That said, I'm in favor of the curve being flattened, but not made completely so.
It's still different.
In a pure tipping system you can opt out by not tipping at all, so it naturally encourages type II misbehavior: false negative.
In Steem you're forced to tip, so you'll make judgement on targets, although perhaps it's random targeted, it's more natural.
Well I did say it was convoluted :D
Another difference is downvoting, which is a pure tipping system won't have.
And in a pure tipping system, IMHO it's easier to manipulate the trending page by tipping to yourself or sock puppets, perhaps it can be limited by a fee bounded or other limitation, but it's still weaker than stake weighted voting. Just my own opinion though, I could be wrong.
I tend to agree it would be best flattened but not completely so. I also have no idea how correct this assertion is.
I read almost all comments on this post and all in all it was a really interesting read.