I think vote buying does not help the human aspect of the community; It'll drive more and more bot generation. Also it does not help quality of content, since the majority of the votes are bought for authors own content. Many Steemians (probably many of the large SP holders) do earn more money than ever before, by running a vote buying service themselves, or renting out their SP to those who run such service.

The comments they place: Yep, I kinda agree they should not be placed. It is indeed advertisement. On the other hand, it can also serve the purpose to those manual (and maybe even auto voters) to not vote for the post when 1 or more votes are bought by the author itself. Not sure if curators actually take that into account. Although I bought from time to time votes (mostly to test it) I do not like these services to be honest. That said, I appreciate the entrepreneurship. I think it was Randowhale who launched such service, and I thought it was very creative thinking. Since then we got so many of these services on Steemit, it almost looks like every day we get new versions of them.

I know it is very time consuming to do manual curation, but that is the only way to keep 1) the community human dominated 2) reward quality 3) distribute the available Steem in a more fair way giving change to the many Steemians at the bottom of the SP pyramid. I would opt for more curation teams to which Steemians can give their SP to, or follow the curation teams with auto followon votes. Curation teams may be the only way to protect the community from becoming more a bot-network over a human dominated network.