Even altruistic voting gives curation rewards especially if it ends up trending. That was the original design right? It encouraged people to add value which brings more and more value to the platform.

Well yes, but the original design was for curation rewards to be 50%, and they also did not have the penalty for the first 30-, 15- or soon to be 5-minutes. The changes that were made later, largely impulsively and without good rationale, undermined a lot of that balance to the point that curation rewards became almost meaningless, and the incentives to just sell votes became overwhelmingly strong.

The hope is that HF21 is going to re-balance those incentives somewhat back toward what you describe, where altruistic or at least non-agnostic voting isn't so heavily penalized relative to vote selling. We'll see how it works out but it's certainly a step toward what you describe.