Here's a positive use case for buying votes from bots like @booster.

Once every two weeks I create a newspaper-like post in which I choose a few posts that I liked the most from the previous two weeks. I set the rewards payout for that post at 1% for me and 99% for the authors that I choose to feature in that post. In that way I try to 'artificially' extend the reward payout for those posts so that authors can earn a little bit more.

For the last two such posts I created, I bought a few upvotes from @booster, @discordia or @worldclassplayer in order to increase the author reward for those two posts so that the authors featured in those two posts will be awarded a little more beyond the upvotes that are naturally received from normal Steemians and beyond my upvote which is worth only 3 cents.

You can check the posts here and here.