Only Nautilus is legitimately comparable because he has two CCs that ignores tenacity and whatnot, but even his has more counterplay because his hook won't go over walls, is slower and can be intercepted. I'll address all of them individually, though, and then explain why the Nautilus argument is a bad one.
Interrupted by allies' CC, Vi's ignores everything except death. Shorter range, and Vi's can be extended by her other skills.
Is the CC specialist and sacrifices clear times, damage output and has worse mobility in exchange for that. Vi and Naut ultimates are like the "True Damage," of CC, because it ignores tenacity and pretty much everything else. It makes sense for the CC specialist of LoL to have it, given that he sacrifices for it, and CC is all that he has. Vi has a lot more going for her than just her two "True hard CC," skills.
I don't play mid lane, but judging from what I've seen playing as her ally and her enemy, she has clear sacrifices that other mages do not. Her mobility is also much more telegraphed, and she doesn't have two gapclosers on top of it. With Vi, keeping your distance doesn't seem like a viable option often times. With Liss, it seems like it is. Slower mobility and less mobility. Can react much faster is my point here.
Can be CCed while ulting to disable it, much like WW, and has no mobility to be spoken for. On top of this, he's squishy as all Hell.
Affected by tenacity because it is a stun, and has no mobility. She's also a one-trick pony. You aren't going to be surprised when she stuns you, she's going to do what every Annie has ever done.Before it's said, Flash is on a very long cooldown and any champion with hard CC could use this. At this rate, you may as well throw 
in the mix for having damage, mobility and CC. Once again, his attack is telegraphed.
Once again, his attacks are telegraphed. He only has a movespeed boost and can be peeled off. Vi can't be peeled because her approach (Ult) will ignore CC. Skarner cannot do this. Even after he closes the gap and ults you he can be CCed to prevent displacement, making it only a suppress.
Vi is unique in that she has a very fast engage, an engage that ignores CC entirely, the engage has hard CC itself, has massive range, ignores tenacity, has tankiness to make it an actually useful engage and still has damage. Of these, only Nautilus is comparable and his damage is awful. He's the CC specialist. Of course he's good at it. The "If it works for one, it works for all," stance is just illogical.
The fact you're comparing a bruiser to a tank's level of CC proves my point about how stupidly designed it is.
