Comment on “Magnetic structure and magnetization of $z$-axis helical Heisenberg antiferromagnets with XY anisotropy in high magnetic fields transverse to the helix axis at zero temperature”

In two recent papers [Phys. Rev. B 99, 214438 (2019); Phys. Rev. B 96, 104405 (2017)], Johnston employs his unified molecular field theory to study the phase diagram of a classical one-dimensional magnet with exchange frustration in dependence of the anisotropy and magnetic field. Here, it is argued that the assumptions made about the stable configurations are too restrictive and not well justified.