Most of the 100%+ curation earners are automatically voting with small amounts in less than 15 minutes on posts that will receive predictably larger votes in the future
Yes, I think that this is the main approach used by the 100+ club. Those predictable votes can come from bid-bots, from dApps with high SP such as DTube / Utopian / Oracle-D, or just from users that consistently receive high upvotes.
I think that there is a second system which involves making a huge number of utterly tiny upvotes on comments that are statistically likely to receive upvotes, but I need to do more research on this.
which has nothing to do with curating content
It is possible to follow the first approach described above using a list of authors that consistently produce good content. But I would agree that this has nothing to do with the "content discovery" idea of curation.
I think that overall the current curation system is broken. This is why I suggest a "flat curation" system - one without incentives so people are free to upvote whatever content they like and are not influenced by gamification.
I agree, thanks for shedding light on this issue. If you want to look more into dust vote curation bandits check out these accounts:
jadabug
hdu
ezravandi
imisstheoldkanye
votes4minnows
delabo
cheneats
elviento
accelerator
penghuren
...and many others.
I think that some of these accounts follow the second curation system I describe above. I need to do more research on it. But at first glance I don't think that it does any particular harm to Steem.
I can hardly blame them for trying to maximize ROI with the current system. Once I noticed them doing this to my posts I created my own accounts to front-run them with slightly higher votes to take back the curation rewards. For example if I vote with 0.002 immediately before they vote with 0.000 or 0.001 it prevents them from taking so much in curation rewards. The problem is there is a limited amount of rewards and time to front-run a large payout post so the more people that do this the less chance a small account has to receive significant rewards by naturally curating without auto bot voting.