While fine-tuning particle effects I often stack several curves in the Curve Editor (e.g. Life Scale, Life Rotation, Life Alpha). Because every curve is currently drawn in the same yellow, it’s hard to see at a glance which keyframes belong to which property—especially once there are a lot of control points.
My best guess is because people are used to use the checkboxes on the left site simply (that’s what I do) But this is a QoL feature that improves Editor nicely