They have ruined recommendations, too, a long time ago. They ruined search, too. If you search for something, it will give you maybe 5 results at best, and as you scroll down, the rest is totally unrelated to the searched term. YouTube has been ruined a long time ago.
It's very annoying if I do want to see that channel, just not THAT video. You also have to be careful with that button because there's no way to selectively unblock channels. There's a feature to undo your entire Do Not Recommend / Not Interested history but not to undo it for an individual channel / video.