It'd be extraordinary compelling to genuinely have a unified mechanism to explain depression treatments, but I am not qualified to make heads or tails of the research. Wondering what the take of those with relevant experience is on this?

Not an expert, but the standout thing about ketamine in particular is that it targets an entirely different neurotransmitter pathway than almost all traditional anxiety and depression meds. Traditionally, people treating serious depression or anxiety rotate through a variety of drugs that all hit same small set of neurotransmitters and settle on the one that works the best/sucks the least.

This is why people get excited about ketamine and psychedelics as therapeutics. Otherwise, we're just sitting around waiting for the next round of "new" drugs that manipulate the same pathways as all the old drugs (and carry much of the same risks).