All I am saying is that there are perfectly good reasons for not using tibbles if you do any kind of work outside of tidyverse. And you seem to agree?

As for whether or not tibbles should be data.frames - I posted a link to this exact discussion on R-dev mailing list within this thread, as an answer to a different poster. Here it is: https://stat.ethz.ch/pipermail/r-package-devel/2017q3/001896...