This would certainly be something that would encourage engagement. Especially new users would get a feel for what kind of content steemstem curates by reading it and at the same time also be rewarded for constructive and meaningful comments. Of course, it would be much better if votes for a good comment would come from the community.
I think the master of how to reward good comments is @abigail-dantes. She adjusts the slider for each comment accordingly to what it means to her or where it should be placed. Just take a look at one of hers psychology posts. The comments themselves are also substantial. I usually don't have anything insightful to say and am ashamed to put my 2 line comment in there so I usually avoid it. But I do read her psychology posts and vote for them. Although she has lost me currently at beer challenge. And its already 14 days since her last psychology post. She usually sticks to schedule. Hmmm... must be the beer :)
I would actually prefer having the community taking care of voting the comments of each other. I am really scared by the scaling of the associated work on our shoulder if we have to monitor comments as well for voting.
You are absolutely right. Unfortunately, some people who have received substantial support from steemstem and passed level 60 reputation don't have even 200sp themselves. In my opininon, anyone who has been rewarded in this way should be able to reward others also. Either through rewarding meaningful comments on their own post or even better rewarding other quality posts. It is the only way to grow.
even 100 SP matters. Imagine we have 30 of such users, this makes 3000 SP. And so son :)