I am not agreeing or disagreeing with anything the author said, nor any references she makes to books or otherwise, however that's such a shallow/basic view of the brain you're putting forward as a counter-point.
The brain and physical-mental-emotional-spiritual body are far more complex than a single physical lever being pulled and a single affect happening; neurotransmitters are the transaction layer, the currency, the current/flow itself.
Likewise, there isn't only a single mechanism or cause of dis-function or dis-ease - the only possibility isn't simply because of a lack of or too many neurotransmitters needing a counterbalance; this isn't to say people some people won't experience benefit from something as simple/basic, however to dismiss other possibilities is naive, and likewise if they can so simply be helped - I'd be curious to see what simple situational-environmental impact has lead them to feeling depressed or lethargic, and whether something like a yoga practice (up to practicing all 7 branches of yoga) would have a greater impact short-term and long-term -- vs. keeping someone in a holding pattern or making them worse; the problem here then is on a societal-economic level, whereby in the short-term it's cheaper to give someone $10 worth of pills every month vs. getting them into a routine with yoga or other; it's also lazy and an extension of how we still as a society treat people - and don't take care of everyone, and that you're lucky/fortunate if you are born into a healthy (physically-mentally-emotionally-spiritually) family with adequate supports and finances, reducing your chances of being negatively impacted by the stagnant, the status quo.
SSRIs/SSNRI's themselves force a change in function by being re-uptake inhibitors, meaning they cause more neurotransmitter to linger in an area - and this doesn't seem to be evenly distributed and/or there is more going on with coping mechanisms, otherwise you could 100% predict the behaviour changes via an increase or decrease. As the author points out, there is relatively short period of testing required for these medications - and they are heavily controlled for vs. when they hit the wild for distribution [and the list of problems there is far too long for me to get into here].
There can be coping mechanisms, blocks, setup by other functions of the brain - purposefully - as a way to protect oneself from something (the ego mind, for survival purposes), e.g. insufferable conditions/experience and overwhelm that the brain/mind can't handle, and so it goes on lock-down. These drugs/medications, from my own experience, and observations of/with others - if it is such a condition with something underlying/suppression/repression going on, protecting oneself from a variety of potential things (injury from physical pain, or other).
Did you know there's a higher rate of suicide (and suicide ideation) if you take certain medications vs. placebo? This can tie into the theory that these medications force changes against self-protective mechanisms. Likewise, it shouldn't be difficult or a stretch to understand someone could be protecting themselves (from consequences), by protecting others, by blocking overwhelming anger and impulses that they learned to suppress/repress to hurt others - resulting in them hurting others, and perhaps in super violent/extreme ways due to not having coping mechanisms blocking them from doing so.
Contrast drugs like SSRIs (et al) with what I will call medicines - like Ayahuasca, psilocybin (magic mushrooms), or MDMA (reference to recent MAPS.org recent study) - that instead of forcing change in mechanism by inhibiting, it floods the brain with higher levels of serotonin that the brain normally doesn't release or have on its own (or mimics closely the serotonin transmitter). Likewise with Ayahuasca ceremonies or MDMA-assisted psychotherapy (or recreational-therapeutic MDMA-assisted dance party with friends you trust in a good environment), there is a contextual setting that will make these safer or more impactful - allowing positive and social pathways to open up (or language pathways relating to talking) - vs. a doctor spending a very short period with them out of context of the life of the person, prescribing an SSRI or other to them and putting them back into their daily life.
I was severely fucked up in different ways because of doctors prescribing different SSRIs (and the like) starting at the age of 17, and the peak/tipping point at 21-22 after more unexpected (or unknown at the time) side-effects - is when I realized I can't trust those doctors, nor those medications, because the industry doesn't actually have a proper fucking clue about them, and it's all an experiment on each individual. The medications had a cascade and accumulative affect on symptoms/problems, making me permanently worse until I could start solving the underlying problems - which ended up being in part food related, in part hearing related, in part from underlying physical injuries I had that I didn't realize I had - and I'm simplifying, it's more complex than that - and hard to believe on the surface, which is why I am writing a book to explain as much detail as possible.
I'm 35 now and only recently had significant healing of physical injury that was an underlying problem since I was a child, through stem cell injections, and will return to the US soon for another treatment to heal more of the remaining physical pain.
I hope you can appreciate your literal "three seconds of Googling" allowing you to come to a conclusion is less trustworthy (on the surface anyhow) than someone who experienced how anti-depressant medications impacted them for 24 years - and then who considers that they had to recover from that experience. I don't disagree that it is complex - and therefore difficult to understand - especially because you have the interplay of what depression, anxiety, and other, can cause behaviourally in someone without the various impact and side-effects of medications.
It looks part of her recovery was finding people she could start building trust to, who then helped her learn about emotions, meditation, and other self-awareness and social-relationship building practices. She also connected to her "inner guide"(or God, whatever she feels most comfortable or comforted calling it) which could perhaps be labeled as intuition, or as an autonomous nervous system working together well on its own without logical mind being engaged; enough learning happened via mind and analysis, to start trusting herself autonomously (trust is or is a part of autonomy), allowing the body to relax, allowing the mind to relax - as there's a feedback loop between the two: the more physical stress - the more mental stress, the more mental stress - the more physical stress.
Linking back to MDMA-assisted psychotherapy gaining benefit by tapping into language and memory pathways of post-traumatic experiences, there are other talk therapies like Innerchild Regression therapy which, in part, explores similarly early childhood relationships and learning to connect or reconnect to those - and understand them better, to process emotion that you may not have been able to before, due to an unsafe environment at the time - allowing those experiences/unhealed emotional wounds, to now start to come up and be healed-processed/learned from.
Anyway, I'm writing a book to share my full story, my experiences with healthcare, the problems I encountered and explain the solutions I propose. It will take me awhile. It will fill in a lot of details here to what I mentioned, perhaps making it easier to understand - or believe. I'm also beginning to put together applications for different stages of research, to be able to reference hard evidence relating to a protocol I've developed based on my understandings and experiences healing, recovering.