  Berta et al [Phys. Rev. Lett., 121, 040504 (2018)] claim that their result
provides a conceptually new extension of the decoupling approach to quantum
information theory. We provide an alternate proof using the plain-vanilla
decoupling approach for the achievable rates of their main result and hence,
their claim is unwarranted, and the title can be misleading when taken in
conjunction with the claim.
