It’s an example of lenses designed for different workflows. Film style shoots it’s not uncommon to swap out a lens in between shots, and focus is sometimes a creative choice. Autofocus doesn’t work when you actually want to shift the focus from one actor to the next without them or the camera moving. You need manually focused lenses with precise control of the focus ring. With touch screens you can get close, because you can tell the software what subject to track, but a good focus puller that’s following the emotion of actors is tough to recreate in software. This is also why they’re generally not designed to be parfocal. Film shoots very rarely zoom the lens while recording.