As far as segments are concerned, MTB, road, and gravel are all under the same “bike” category.  They have only recently been split out into their own separate sub-categories, but are combined for any leaderboards.  Same with e-bike and e-mountain being combined together.  Those and velomobile are very different activities altogether from regular biking.  

I do agree that it would make sense to split skate and classic ski into two sub-categories, but still should remain under the “nordic ski” main sport type.