I think commentrewarder is a great initiative to stimulate engagement on Hive.
When comments get rewarded more people will have an extra incentive to engage more (although I doubt if a financial reward is a good incentive).
A 'shortcoming' of commentrewarder is the fact that a post needs quite a bit of author rewards in combination with a higher percentage for the commentrewarder beneficiary to result in a payout for the commenter. As you might know values under $ 0.02 are considered as dust and will not be paid out.
Maybe I'm wrong, but I don't think commentrewarder will work for new Hivers.
I'm also working on an idea to improve engagement on Hive. As soon as I have more details I will publish a post about it 😊