I would address the haejin problem myself by ignoring it.... in that, whatever haejin staked himself... he's basically just a speculator when he self-votes... it's the reward he gets for staking his money. If he posts garbage content, then no on else will upvote his material and he'll simply be treading water in the long run because the constant creation of Steem is built in inflation and he'll just keep breaking even on his stake if he continues to self-vote. Thus, he doesn't do any real harm... because only his subscribers actually have to see his posts (so it's not spamming me for instance). If some weird people actually find value in his stuff, well, that's fine, let them upvote and he gets paid just a little bit on top of his gigantic stake... drop in a bucket.

The problem happens when some other whale comes in and decides to create some drama by unleashing a bot army on any one who even has an opinion that differs slightly... such a whale using the excuse of "fighting bad actors" to justify actually being a bad actor. This supposed do-gooder whale has driven more people off steemit through his downvoting and account crushing actions than Haejin ever did by stupid market analysis posts that I never bothered to read or was ever troubled by... so what if he self-voted... the whole game is based on inflation so he's not actually making any money from self-votes. In fact, anyone who self-votes... should be justified in doing so to the maximum level they desire... since they "earned" that right.

I'm a nobody plankton (or whatever) and I don't have ANY spam in my feed because I don't follow spammers. So I have trouble seeing how downvoting spammers or plagiarists.. or whatever, does any good at all?

I feel like upvoting is the only valuable thing that happens on this chain. Maybe I'm wrong, but that's how it looks to me after a little bit of time around this block.