  In a recent series of works [Ebler et al. Phys. Rev. Lett. 120, 120502
(2018); arXiv:1809.06655v2; arXiv:1810.10457v2], it has been proposed that the
quantum superposition of causal order -- the quantum switch -- may offer an
enhancement of classical and quantum channel capacity through noisy channels, a
phenomena that was coined `causal activation'. In this paper we attempt to
clarify the nature of the purported advantage, by comparing the quantum switch
to a class of processes that can be interpreted as quantum superposition of
processes with the same causal order. We show that some of these processes can
match or even outperform the quantum switch at enhancing classical and quantum
channel capacity, and argue that they require the same resources as the switch.
We conclude, in agreement with Abbott et al. [arXiv:1810.09826v1], that the
aforementioned advantages appear to be attributable to the ability to
coherently control quantum operations, and not to indefinite causal order per
se.
