"Tanks counter assassins"

Except assassins build items that shred through your armor like it's nothing, so not really. They can also build botrk which lets them shred through you even more easily. They also have abilities that make them untargetable, so avoiding your cc is easy. They can also bypass the frontline very easily, due to the mobility from their items and abilities. With even a small amount of magic resist (as well as other items like death's dance, edge of night, maw, etc), your damage becomes laughable and you can't touch them. And the cooldowns on their items are much shorter than the cooldowns of tank items, so they have more opportunities to make plays than you (in fact, assassins are knows for having super short cooldowns, so they get to run around the map making 'plays' all day while tanks get to do nothing because of stupidly long cooldowns). And a lot of them hyperscale (Rengar, Zed, etc), so their late game will always be better than yours assuming they get at least a couple kills. Please don't give me this "high risk" bullsh*t when it comes to assassins. They have so many ways to avoid tanks and kill them it's stupid.