My question to you is:

What economic model have you used/consulted that proved to you that it is better to "spread the wealth" in terms of votes vs. say people getting rewarded based on their purchased (or earned) stake?

Because from where I am standing, it makes a lot more sense that being rewarded based on your stake would create more upward pressure on the price of steem vs. the alternative of "spreading the wealth" in terms of voting on new and/or different users based on some arbitrary definition of "quality".

The second option seems like it would encourage people to show up, post for free, get some earnings and cash out those earnings. Not much incentive to power up (beyond some curation rewards) compared to the other incentive, where there is a direct correlation between the more steem you buy the more you earn.

I'd be curious to see what the economic theory is behind this line of thinking.

The number one goal here should be to create as much demand as possible for steem power, everything else should be a distant and far second.