I don't see why everybody is so annoyed by supergirl and want her nerfed. I play against her everytime I'm on because of all of the tier whore bandwagon and I don't see her needing any nerfs. Think she is fine I never felt cheated by any of her tools.
I think you're confusing "Honest" with "Viability"
They are not the same thing.
A character can be honest and too good.
Same Vice versa... a char can be dirty AF and be ass viably (look at Joker)
Outside of the crustyness SG is honest she has nothing on paper that screams "Broken" but that doesn't mean the char is fine.
She has no losing MUs ,that's fine too, but what is not fine is having no weakness or flaws.
Not only that but in most MUs she beats chars in a lot of elements (Offence, Defence, Neutral, Air , zoning, counter, ect) and at worse is on par.
So there is 2 options to help improve balance
1. Get everybody to her level.
You know that direction will cause more problems in the long run
2.Bring her a down closer to the base level.
This is the most problem free option
CW on the other hand is too good more on her dirt so she's on the other spectrum.
Disclaimer: I'm not complaining about the balance of the game at all, in fact check my statuses I compliment them and think this is the most balanced game by far they have ever made. But that doesn't mean they can't make it even better