Yeah, MC barely had a good live vocal performance during the Butterfly era even. Her live performances of My All and Butterfly were shaky. She started lipping a lot on tour, something she never did on her Daydream tour. And by the time she released Rainbow, she didnt even execute a good live performance to her easiest song to sing that era, Heartbreaker. Glitter she didnt give us anything and by the time Charmbracelet came around, her vocals couldn't "make it through the rain" one bit.
The thing is, anybody that disagrees, all u have to do is simply post a performance of Mariah from the Butterfly/Rainbow era that was solid and near flawless and we'll shut up. But yeah, no one can.