IMO this is really Kagi's killer feature. If I see a poor behaving site (Pinterest, for example), I can easily exclude the domain from every search I ever make. I don't have to carefully craft an enormous search query of all the sites I don't want to be shown. Demoting news sites that have a reputation for promoting bad takes, and prioritizing results from sites that are known to be good.
The quick switch to move to reddit based search, or old web results, are also great, but for me, it's the tailoring of my results to what I actually want, and more importantly, what I don't want is what sold me.
FWIW, it's much better to downrank a page than to outright block it. Blocking is for a page you never, ever want to see.
I personally dislike Pinterest and TikTok, but sometimes it might be the only source of an image or video. Blocking means you don't get to see that result.
Most of the time I agree with you, and prefer downranking, but I have to take issue with your example of Pinterest, because my experience with Pinterest is that if I'm searching for a specific image, I will always get a thumbnail of exactly what I want from Pinterest, but when I click on it, I'm taken to a page of completely unrelated results. It is beyond frustrating, and specifically blocking Pinterest was one of the primary features that sold me on Kagi.
The quick switch to move to reddit based search, or old web results, are also great, but for me, it's the tailoring of my results to what I actually want, and more importantly, what I don't want is what sold me.