Like I said, he gave no context, therefore your view is technically right as well, but then it comes to to the point he was obviously trying to get across. Questing in general isn't mandatory and common sense would tell anyone that, so it should've been quite obvious that he didn't mean it in that sense.
Besides, that point is easily solved by having solo quest lines separate from quest lines that would be entirely group centric.
I feel this is the point he was trying to get across.