I miss clicked on Swain but the point stands she can be beat and she has to burn mana to get away, she can be kited, and wrecked but instead ppl want her basically gutted because if you can't beat her complain she's broken and needs to be gutted. If it's not charm/ult it's her q ms boost. Again she's gated by mana on her q and if you play smart she'll either run out of mana really quickly or have to avoid engaging if you play smart.
Talon, Annie, fizz, Swain, Lb, Galio etc all counter her hard. If you want her MS nuked again you'll get something given back to compensate that you'll complain even more about. I've played Ahri since release as well and after the DFG removal and all the nerfs she was basically a free kill hence they gave her the ms boost to make up for it.
She was difficult at 1st to get used to but once I did she was a lot of fun to play with but I also ran into ppl who knew how to play against her and usually I got wrecked or I had to play so safe it was pretty much the same. If those complaining about her would actually play her and nothing but her they'd see she can be countered.