But do the solo duties actually prepare players for playing in a group?
I doubt that very much, and especially with the solo duties starting in 4.3 where we begin playing as NPC with abilities that either don't or only vaguely align with playable job abilities.
The solo duties are there as a story-telling mechanic, not to prep players for group play. Players will have already experienced the mechanics involved in the few solo duties that involve allied NPCs.
When you touched on cultural difference in your previous post, I think you hit the actual answer. There is a stark cultural difference between JP and NA.
JP has a noticeably higher completion rate in Savage than NA because success of the team is important to them. If they run into problems, including someone underperforming, they don't rage quit. They work to find ways to get past the problem together.
NA has more of a "every man for themselves" attitude. If things don't work right the first time, you quit and find another group where they might. Few players will acknowledge that they might be the problem or feel that they need to improve.
So I'd say that SE likely does have some expectation, within reason, for players to carry underperformers. It's not an absolute - vote kick and vote abandon are always there. But they want parties to at least attempt to solve problems together before giving up and that's something that a lot of NA players aren't interested in doing. They want instant gratification and success the first attempt, and that sort of attitude can hold success back because people aren't being given the chance to learn and improve.
