FAFO is just "karma" re-articulated, it implies those who do wrong will receive consequences for their wrongness - it implies the universe is just and that innocent people don't get punished.
Usually rather than admit that nature is not just, that innocent people get punished and hurt for no reason, people instead try to rationalize ways that victims "deserved" it.
For example, the Buddha taught that with enough loving-kindness in your heart, you can become invulnerable to harm from animals, so when one of his monks died from a snake bite, he claimed the monk must have not had enough love and kindness in his heart for the snake to deserve being bitten.
In reality, sometimes snakes act irrationally and bite people who aren't messing with them. This can happen because the snake was stressed by an unrelated event, or because of disease or illness (much like a dog can attack because of rabies).
Ultimately karma is not just a lie, it's a system of gaslighting victims into believing they deserved the bad things that happened to them.
