good questions! I have some of the same ...
One can argue that pile-on effects ,robo voting and the like are abuses in the strict sense because they do not value the post, they are speculative in nature.
Up votes to me don't seem like curation, in the sense that to me they are not a strong signal that the post in worth my time .
Because I know that the upvote system is used for speculative purposes, I don't follow the hot and trending lists.
A much stronger signal of quality is # comments and re - steems by people I follow and respect. I wish these factors weighed heavier for author rewards.