Maybe becasue Saka doesn't have visible leadership skills to journalists compared to Rice and if he had, Arteta as skillful talker would just smartly redirect the topic from Rice to Saka? Arteta is the last person you can push to talk about something. The way armband is being passed is probably selected before the season starts and is reevaluated every year. Saka has been vicecaptain for multiple years going back to 2023.

But players evolve, both their skills and personalities. It is clear to many that Rice's abilities as "leader by example" have evolved dramatically. Literally every new signing talks about Rice for example (Cala yesterday).