Bears are not meant to dance. They are meant to lumber, and eat berries and salmon, and sleep and scare people. And when they are forced to dance, they are really bad at it. And yet for centuries people have captured bears and spent years training them to lurch around on two feet. It's hard work for the trainer and it's harder work for the bear, and the trainer does it just so people will say "Wow, look! A dancing bear. I've never seen that before!"
The entertainment here is not to watch brilliant choreography, but to marvel at the fact that the bear can dance at all.
We, as writers, capture virtual bears and force them to dance all the time. We get an idea, and it sounds cool, and we work and work and work, and actually make it do what it's supposed to. Maybe it doesn't quite fit, but with a little more work, we actually do make it fit into the flow of the story.... And it works.
But it doesn't work well.
But it was so difficult and tricky, that when the time comes to ruthlessly edit the story, we are too proud of having made the bear dance at all to see that it's no Fred Astaire.
I suspect that this is what some people really mean by "kill your darlings." But they're not always all that darling. The truth is you may or may not love your dancing bears. You may just have committed yourself to it with so much work that you don't see how you can replace it.
The goal is to be most proud of the actual best things in your story. The goal is to learn which things these are, so that you can make the ballerinas into your prima donnas (your darlings) and chase the bears back into the woods.