One view - among many - in Marketing holds that value is not created in the manufacture of the product, but in the experience of the customer. Seen in that light, what happened, and how it works is each of ours to determine individually.
For me, Steve Rogers (or whatever identity he adopted) had been waiting on the sidelines to hand Sam Wilson a copy of his shield since the late 1940s, and watched it all happen, from Iron Man through to his old friend's funeral, having faith that he and his dearest comrades had what it took to work it out the way that he remembered. If he was tortured by letting history pass around him without trying to make it better, he took solace in the knowledge that tinkering might dangerously interfere with what needed to be in ways he could not predict, and in the joy of life with his beloved Peggy and their children.
In some ways, for a man so conditioned to action, letting history take its course might be the greatest battle Captain America ever fought.
The Question That Remains: What are the children of a Supersoldier like?