Of course it should be the first line of defence, realistically it's the only line of defence when it comes to chemical compounds.
It promotes neurogenesis whereas most other substances are neurotoxic and have awful side effects, suicidal ideation? Seriously, that's the opposite of what you need, you don't want to feel numb, you just want to feel something other than sadness, restructure brain to the birth state and boom, you realise you can experience what feelings you want, when you want.

The entire idea is that you realise or learn what life is and how you should be living it, you dispose the idea of self and know only outward love.
If Entheogenic plants do not work, the only other thing that would is changing your life entirely, this is generally not possible due to our society and the requirement of money and 'land ownership' to survive which is completely immoral, it's a different argument but to say Psychadelics don't reveal this revelation but still intertwines