It sounds like there's a lot of disagreement about whether or not feedback over merit abuse is appropriate, but I was under the impression from the start that this was something we weren't going to tolerate.
DT members haven't been consistently tagging suspected merit abusers, and part of the reason for that is because Theymos doesn't really want us to. Begging for them by PM'ing members crosses a line IMO, but others may disagree. There are no rules as far as tagging merit sales/trading/begging, just Theymos's opinion on it. I've received maybe a handful of PM requests for merits, and I'm pretty sure I've negged each one.
Also, there's a difference between someone just saying "can you pls give me merit" vs. a member asking that you review one of their posts to see if it's merit-worthy. The latter case doesn't deserve a neg IMO, and it's something I'm actually quite happy to do (review a member's posts).
Neutral feedback is useless in these cases, because it doesn't send any sort of message to the beggar, doesn't prohibit them from continuing to beg, and doesn't punish them in any way for doing something wrong. Most of us know why Newbies need 1 merit and why it's so important to them--it's so that they can start advertising in their signature, and that usually presents in the form of shitposting. If a member has to resort to begging for a single merit, their post quality is probably going to be very sub-par.