But the whole point of the article is that given the way modern hardware and kernels work, you don't actually have the ability to program against lower layers of abstraction, and attempting to do so can degrade performance.
In fact, Knuth’s aphorism is a much better description of why one should avoid the complexity of this issue than a clearly incorrect argument proposing that the distinction between storage classes doesn’t exist, that 1975 programmers were ignorant of storage abstraction, and that this issue has become less complex over time. (Edit: corrected typo. Programmers in 1075 were definitely unfamiliar with storage abstractions.)