Regarding to what you all discussed about the negative feedback on spammers (or neutral), let's see theymos' opinion on this.
- Giving negative trust for being an annoying poster is inappropriate, since this has nothing to do with their trustworthiness. If they're disrupting discussion or never adding anything, then that's something for moderators to deal with, and you should report their posts and/or complain in Meta about it.
As far as I know of, @The Pharmacist and @actmyname are the two (at least ?) who pioneered to leave negative feedbacks on spammers because of massively terrible spam endemic on the forum circa late of 2017 and early of 2018. I don't know where they began to report and tag spammers but I read their replies in some threads about their works back in that period.
They claimed that they stopped leaving negative trusts and reports (reduce in intensity) after the merit system was kicked-off.