I'm not concerned for me, I'm concerned with what less sophisticated people are willing to put up with.

Our options are convenience of device sync or one password.

Or some other mechanism, because I have been told in no uncertain terms that's as far as it goes.

I can't even convince this family member to rotate their passwords. What makes you think they'll be willing to put up with more inconvenience?

Again, the problem is the unsophisticated user who only has so much brain space for this shit.