Comment on "Is Dark Matter with Long-Range Interactions a Solution to
  All Small-Scale Problems of \Lambda CDM Cosmology?"
  In Phys. Rev. Lett. 109 (2012) 231301, van den Aarssen et al. attempt to
solve all the small-scale structure problems in the cold-dark-matter scenario
by introducing interaction between the dark-matter particle and an MeV-mass
vector boson. In addition, the latter is coupled to ordinary neutrinos, and the
neutrino-vector boson coupling constant 10^{-5} < g_nu < 0.1 is required for
that purpose. We show that this dark-matter scenario is subject to restrictive
constraints from Big Bang Nucleosynthesis.
