You said: "What happens when good players group together."
I was just giving an example. Sry. Didn't mean anything against your view point at all.
Just inspired to answer that part of the question from my point of view.
And also, many of those players I enjoy grouping with are quite capable of soloing many of those same quests. They just enjoy the company, and don't want to take the time it would take to solo, or maybe the resources.
A RL friend of mine used to solo a lot of quests. But when we would do them together (2man) he would comment on how much easier it was.
I wasn't good enough to solo the same quests he could, but together we could do many quests with ease. And he had no fear of getting held or some other deadly failing of a save.
And we could use tactics that one person alone could not use.
Anyway, sry...wasn't directed at you, as much as it was inspired by your words.