Also, he gives "more of a language reference" as a reason for not reading Stroutstrup's C++ book. Doesn't the same apply to K&R?
It's probably impossible for any book to fully describe C++ because it'a a perpetually moving target on a three year update cycle.
There are always new idioms and techniques to learn, but they keep being changed/added without any obvious coherent design strategy or logical goal.
Books can barely keep up. Stroustrop's own C++ introduction is for C++11, which is already five years and nearly two releases old.
The end of the book even included a grammar for C++ (with a slight comment about how the grammar wasn't exact because of C++ context sensitivity)
In 2016, however, I think that a lot of people would have read CLRS, even if they haven't read ALL of it. It's used as the reference text by a lot of university courses on algorithms.