As someone who has aged, I gotta disagree.

In high school, 20 year olds were ancient and wise.

In college, 20 year olds became peers and competitors

Once I started working, 20 year olds were the newbies

Now 20 year olds are indistinguishable from babies. Just having a conversation that ends with "After this we're going to the bar, you want to come?" and getting told "Uh... I'm not quite old enough to drink" blows my mind every time I hear it.