All it takes is someone to have their phone mounted on a stand near their wheel (one of the vent mounted ones would be what I’m thinking), and then they could scroll to their hearts content. You only have to pause temporarily to shift gears, and even then I don’t think it is making you any less distracted. You’re just now distracted by shifting gears too, which takes your focus off the road to some extent as well.
The “distraction” is taking your eyes and mind off the road. A car that has an automatic is inherently less distracting overall. It has a higher tolerance for people to scroll or distract themselves in another way such as their phone, yes, but the amount of focus needed to not veer off the road or crash into something is the same regardless of how much baseline focus is needed to generally operate the car.