I doubt that anyone is going to be denied a job because they are an amazing R programmer but they just don’t have the experience with a particular set of packages, especially those that are as well implemented and easy to learn as the Tidyverse.
I can totally imagine someone not getting a job because they are a crap programmer, and then blaming it on something else. Or I can also imagine someone saying that the Tidyverse packages suck, and then be denied a job because of their attitude.
I could make a similar argument for most of the substantive claims in his post.
Some of these examples (dplyr vs. data.table) are cherry picked. I have several of my own examples where read_csv is way faster than read.csv, so maybe, like all good programmers, we should be testing and profiling our code and implementing the parts that make the most sense for our needs.
The bottom line is that the Tidyverse is a good set of packages and you are free to use them or not. There isn’t some blood feud (like vi vs. emacs) between users and non-users, we all get along just fine.
There are dozens of great tutorials on how to learn R that don’t use the Tidyverse, and RStudio is under no obligation to offer a full course on every possible way to learn R. Any R user is also a competent Google user.
It’s fine to be opinionated. But, a professor as respected as Norm Matloff should be careful of how they say things, or they risk souring their students on a set of packages that might be very useful in the future.