I know that it was done to combat comment spam. I'm not sure what the math is behind it. You can observe the impact by voting a fresh comment as opposed to a fresh post.
Is this because I benefit when Hive as a system becomes more valuable?
That is my opinion, more of the reward pool directed towards authors, provides incentive for more authors.
Or because comment upvotes don't produce good curation rewards?
Aside from being downvoted, you don't get the benefit of content discovery. Earlier voters reap the benefits of larger voters coming in after them. The following is a good example: https://peakd.com/hive-174578/@ybanezkim26/free-speech-has-no-alternative
Below is the curation reward I received for voting relatively early, which far exceeds the input of my vote:
However, the comments and posts I manually upvote provide content that I personally care about and that are of high quality.
I'm with you, but what does this have to do with your own comments? You vote every single one of them.
https://peakd.com/@dhimmel/payout
The last thing I want to do is put you on the defensive, but how can I as a curator, and steward of the reward pool think this is a good allocation of a finite resource? To put it selfishly, how does does this allocation of the reward pool (you incentivizing yourself to comment invisible to anyone else) move the needle for me, how does it move the needle for the platform in terms of promoting the creation of more indexable quality blog posts?
So I guess my bigger question is are we pushing users too much towards curation trails?
It's possible, I have just a little HP dedicated to trails on an alt account. Aside from that all my curation is manual. If I didn't have the time to do this, I would most likely trail follow someone I trust, it could even be an individual.
Take a look at what is happening over on STEEM if you think that consumption of the reward pool by stakeholders increases the value of the platform (i.e. existing holdings). Our long term success as stakeholders depends on enhancing production, not our own consumption. We enhance production by creating value ourselves, or by rewarding people who seek to create value on our behalf.
The reasoning here is more tenuous, but the idea is that some of my comments exceed the value of my max upvote, such that in aggregate my self-upvotes should not exceed the total value of my contributions.
But since I've stopped self-upvoting comments, this is no longer important.
Having plentiful high quality commentary on a post increases its value and can end up driving traffic. Reddit, Quora, and StackExchange are great example here where the initial post is often of little value compared to the responses / discussion.
Also I think there's an opportunity for frontends to rank posts by net comment rewards to drive viewers towards content that is getting meaningful engagement.
I agree this is somewhat separate from the self-upvoting discussion, but I'd like to consider ways we can do better at encouraging interaction.