this is not the usual way of big company handling their group tho.. like SM with SNSD for example Yoona is the main attractor back then but the management know how to push Taeyeon, Jessica, Tiffany etc.. also TWICE, Nayeon is the main attractor but you dont see JYP rubbing Nayeon face on each of us every single time, even during their early day (Cheer Up era)
what part you don't understand that is up to them ( music shows, radio shows ) if they want to put her on a thumbnail if you every watch the shows they go to......many members are getting attention like rami and to some extent asa it's not only ahyeon.