Disagree. I leave feedback when it can warn another customer of something unexpected.
A while back I left negative saying paint-pencil pens arrived from China dried up, and even soaking in solvent wouldn't bring out any pigment. Twice, two different vendors. One complained that a negative would hurt them, also they wouldn't be able to sell any more of the markers - but they didn't offer a refund. I replied shutting down their selling of useless pretend non-markers was what I intended to accomplish with the negative.
Also I've left negative comments on Amazon saying buying Ryobi stuff at Home Depot (the trademark owner) is tens of $ cheaper than the same thing in an Amazon listing and has a useful warranty, in contrast to what some re-seller is offering. Likewise with HF stuff. I'm sure those 'vendors' just run to HD or HF when they receive an order for their overpriced listing.
Feedback is useful.