Every engineer and PM (there was only one) I knew on the team was aware of the origins of the Paper codebase and the connections to Wave, since it was a fork of Hackpad (acquired by Dropbox) which in turn was a fork of Etherpad (acquired by Google).
What year was this focus group?
I liked Dropbox Paper, and tried to get several projects I "owned" at my company going on it. No one, and I mean no one, else could grok it. We defaulted quickly back to laborious email chains. Grrrr.
It's odd how some tools seem intuitively useful to some kinds of minds / work, and not to others. The Wave / Wave-like interface has an appeal to techies, and was responded to positively by the the theatre professionals with whom I used it in ~2010. Paper was utterly rejected by the biz-dev sorts with whom I work now. I suspect that has something to do with creating something new vs uncritically applying known algorithms. But I don't really know, and that may be an uncharitable analysis.
A few years ago I was invited to a (pre-release, I think) focus group at Dropbox headquarters on their Dropbox Paper project. We went around the room, speed-dating like, to different tables, where PMs and/or engineers showed us particular UIs or use-cases and asked for feedback. At every table I told them that "this looks a lot like Google Wave", and was met with blank looks.
There are downsides to the tech industry's extreme youthfulness.