I mentioned stealth explicitly.
My main point here is simply that solo duties could be used to improve player competency, but in practice they do not, particularly when we play as someone else. One might argue job/role quests do this, but the recent healer line seemed to mostly involve being told to use Esuna and pressing the right button. That's not teaching healers anything about playing well in dungeons.
Most of the solo duties teach you how to do that solo duty. Broader applicability is minimal.