People aren't learning excel because Universities are part of some Microsoft conspiracy. They are learning it themselves, or from each other.

My mother self-learnt excel, first as a to-do list, then a money tracker, then she learned some simple equations to keep track of weekly spending.

How in R would someone do that? With a nice graphical view? I agree Excel has many many issues, but people use it because, in my experience, it super easy to use and in particular let's you easily mix data and code.