Have you seen all USA matches? If not then go watch! You comparing NT to club team or USA karch to guidetti in vakifbank - that's what you call irrelevant. Team captain should always be in the court (most of the time) to take the role and responsibilities as acaptain. When you see larson playing and not doing well then don't expect karch will sub her out that easily and it affect his decision making. Have you seen vnl or world champions where almost all OH played libero. If we haven't seen kelsey switching from OH to libero in world championship we will never realised she is perfect for that position why will you not do that in olympic if that's the key for winning? Unless switching position is prohibited in olympic.
There are many team captains who doesn't play as starter in NT as well. Chirichella in italy as an example won't be starter for sure and there's a chance that she won't even make the OG roster. You really exaggerate the role of team captain