The articles point was that markdown (or other similar utf-8 text based documents) is the best guarantee you have for the files being usable into the indefinite future. As you get into the complicated formats of things like word processors the less likely that format will be meaningfully usable in 10,20,50 years time, good luck reading a obsolete word processor file from the 80s today.

Its nice that you inform people that they cant tell if something is saving them time or not without knowing what their job is or how they are using a tool.