There's a difference between adapting for mirrorless versus adapting for cinema. They're not just throwing on an adapter to change the distance to the focal plane, they're actually rehousing the lens. Usually that means adding a de-clicked aperture and reducing focus breathing. These are all primes, but cine lenses are usually parfocal as well.
To your point, none of those things are important if you're just a regular consumer and taking stills, but they're all really nice to have/important if you're working on a film.
> There's a difference between adapting for mirrorless versus adapting for cinema.
The article says they’re adapting to mirrorless cameras
> As reported by CineD, the new Air series of lenses is designed to cater to the growing number of filmmakers who are using compact, lightweight mirrorless bodies for high-end professional work.
> The IronGlass Air lenses move away from IronGlass’ standard PL-mount cinema design toward compact, mirrorless-friendly designs