Some discussion of pharma-psychiatry stuff, i haven't gone through to verify claims (whether it's some crank journals), but the gist is that antidepressants show effectiveness around placebo for depression treatment, and thus not getting success from them and getting approved for ketamine shouldn't inspire confidence, as it shows the same effectiveness.
(obviously not a call to abandon medication if it helps you, who it helps - it helps)
single injection and short term efffects are there, but long term seems whatevs (?)
people sometimes misunderstand placebo point as well, that people believe it's medication. You eating sugar tablets you self-prescribed would help much less than eating sugar tablets prescribed by a doctor. So if they suggest some medication, it still might help randomly (or by matching your issue)
Placebo effect can be pretty strong, then. At least that's one way to think of it.