Not sure Mario's the best example here...C2's platform behavior is fairly capable of that. Thing is, even if the platform behavior is suitable for your game, you're still going to have to put up with all of this:
-There are occasionally gaps between the platform object and walls
-Can't fit into space equal in width or height of the object
-Can't fall into small gaps in the wall or floor, even at slow speeds
-Can't be pushed by solids without shaking or being propelled upwards
-"Pops" upwards when jumping around edges
-Jump height varies with framerate
-Sometimes clips edges of platforms without triggering "is on floor"
-Gets teleported to the top of jump-thrus when ~16 pixels from the top and moving horizontally
-Has no ceiling or wall slope detection
-Can't disable certain components if not needed
-Can't retrieve certain properties
-Can't toggle collisions with certain objects
-Can't be modified to work like the platform engines in, say, Sonic.
-GAME BREAKING bug where behavior gets stuck in-between falling and landing. This has been reported numerous times. It locks your player to the ground and you cannot jump.
and there's no raycasting and point collisions and all that jazz for, say, perfect wall-tracing and detecting slopes...but that's another topic I suppose.
...Anyway, all that's just off the top of my head. I've played around with "beginner" platform engines in MMF2 and GM that don't have any of these issues. And you should keep in mind the platform behavior has been around for like 4 years now...if it's based on CC's then that's more like 7 years. Similar lists can be made for just about all the behaviors.