Here's the thing about Volibear compared to almost everyone else on that list and this isn't exclusive to him; He can't miss. At all. All of his spells are only barred by range much like Garen, Kindred, and Nunu. Because when they can't miss, numbers are the only metric of balance. Should something, ANYTHING make those numbers insane they suddenly become top picks.
Remember when Xin Zhao was buffed and his numbers were actually good? Yeah everyone hated his guts because he just jumped on you and smacked ya with a literal stat-stick with nothing you could do to avoid the damage. Now give Volibear actually good numbers, replace the dashing with immense bulk and you got a similar case.
Kog'maw can miss and is somehow squishier than Sona so he needs a team comp built around him.
Tristana can only miss her jump, but she can also save an enemy with mis-timed ults. Sure Volibear can also save an enemy, but only if he flips them over a wall which is a much rarer scenario, at least relatively.
Twitch is definitely a problem, but he only has team-fighting to make him stand above other ADCs as in 1v1 scenarios every other ADC not named Kog'maw as the other ADCs have damage steroids.
Cho'gath R+Stoneplate will go away when Stoneplate is nerfed. Riot sees Stoneplate as the offender here as it caused a lot more than just that boost to his R damage.
Nunu is outdated and in need of a VGU
Mordekaiser is outdated and bug-riddled and in need of a VGU
And Pantheon was never seen as okay. Ever. If Renekton, lane bully and balance metric of top lane, has to respect Pantheon even if he does dive face first into the grand canyon come late game there is a serious problem.