Well, in my opinion there is not vote buying. The post published in FreeCompliments Community are curated (always don't be spam, plagiarism, hate speech, etc.). The percentage of the vote depend on the quality of post, every curated user receive as well 1 HSBI. There is users that post daily in the community (usually reports of giveaways, investment or things like that) and for that reason are almost permanent on the Rewards report. This kind of post normally receive a 10% or 20% upvote (less than 0.004 in rewards). The upvote is not guaranteed.
The delegations come in as a way to users to support the Community, as well almost every community receive delegations of the users that post there.
Hopefully this disipate your Concerns.
Edit: I am talking here how FreeCompliments and @fc-rewards works.