I don't think they are a good systems because how much "appreciation" you can show depends on how much money you have.
Discussion
Only if you think of appreciation as a competition. For me it's not about how much, it's about having a change in awareness. In fact, I agree with you that participating with a response is a great way to provide value. A reaction is still a signal, but it is a low-effort feedback.
Personally (and you might agree with this) I think a comment, even a very simple one, is a "greater effort" thing than a payment.
(Which may actually be an argument in favor of either, depending on the circumstances).
It depends. If I think the user posted a piece of content looking for a v4v rationale, for example, a journalist posting an article, I try to act according to what I think for him is the greatest value at that moment. A response doesn't help him pay the bills :)