I know that it's not so simple to implement and also not 'perfect' (already these days some replies mentioned the problem of users with multiple accounts), but I do think ideas like this could partly make 'circle jerking' less profitable and less easy to execute.
It's part of their job to think these things through and find out how big the probability for it to really work is.
Good to know that they are seriously discussing these things.
If something is not perfect, and at the same time it hurts honest users, it shouldn't be implemented.
Exactly my point about the curve when I think about it that way :D
I don't see how it would hurt honest users: even my best friends I don't need to upvote several times per day (or even every day) ... :) And I still could do that, if I insisted to, I just had to accept somewhat lower returns.
For example the curation window hurts me much more than diminishing returns ever could, as I never try to upvote any post within the first five minutes after it has been published. I can't find good articles that fast if curating manually (only auto voters can) and even if I did, I couldn't read and evaluate them within five minutes. As a result nearly everybody with a comparable STEEM power earns more curation rewards than I do ... but the good thing is: I don't care that much. :)
Anyway: you prefer the current state to solve the problem by downvoting abusers it seems?
Well no, I don't. But at least it's kinda visible when they stick to the same account and don't constantly switch through several. It's not really a solution, because it would hide the abuse even better when someone decides to do it.