Funnily enough I am a Janna main(second highest mastery behind Sona), and Janna has that ~54% winrate across pretty much all tiers from Bronze to Challenger atm.
It's called objectivity, something you obviously lack because you feel that just because a champion has a "counter" it means it must be meaningfully balanced.
Anyway, by your reasoning, you should use your brain and pick another champion instead of bitching someone banned away your one trick pony. Cognitive dissonance and hypocrisy at its finest.