It's not about doing the job, at least in most teams. Being a manager involves maturity, workplace experience and a confidence that is rare in young adults.
Being able to assess situations and support staff is a complex job that I just don't think a 22 year old is suited to. Albeit, be a senior member of the team technically, but not managerially and not a team of older, experienced workers.
How many decent managers have you had in your life? I've been badly managed by people of all ages. Age doesn't necessarily confer maturity, knowledge and good judgment. I have only had two really good, engaged, professional managers over a 40-year working life. One of them was younger than me and mature beyond her years, one was the kind of older, wiser manager that we all long for.
Anyone with management experience will understand the problems that arise in organisations where the 'lifers' hold back innovation and cling to the status quo. The set-int-their-ways 'But we've always done it like this' brigade would have given anyone, whatever their age or experience, a hard time.