No longer shunned, the asymmetrical style is being embraced by some of the most followed women on the planet: The actor Zoë Kravitz has been smoothing her bob to the side; the singer Addison Rae channeled Marilyn Monroe with her side-parted Grammys look; Paige DeSorbo, a podcaster, adopted a side part and made it a whole topic on her popular show “Giggly Squad.” Some of the most faithful center-parters of the 2020s, from Representative Alexandria Ocasio-Cortez to the beauty entrepreneur Hailey Bieber, have shifted their parts to one side in recent months. A revolution is afoot — or rather, ahead.