  We present a simple biophysical example that invalidates the main conclusion
of "Nat. Commun. 10, 3542 (2019)". Moreover, we explain that systems with one
or more hidden states between at least one pair of observed states that give
rise to non-instantaneous transition paths between these states also invalidate
the main conclusion of the aforementioned work. This provides a flexible
roadmap for constructing counterexamples. We hope for this comment to raise
awareness of possibly hidden transition paths and of the importance of
considering the microscopic origin of emerging non-Markovian (or Markovian)
dynamics for thermodynamics.
