Applying rules of thumb takes a heck of a lot less mental effort than tossing everything into a mental bucket of "other people's experience" and then drawing on specific aspects as relevant to the situation.
But rules of thumb about how people generally are inevitably lose fidelity for individuals, making then often entirely wrong.
For example anxious people find certain things help their quality of life, but those things may be toxic to someone without an anxious disposition.
In the same way that we love someone who 'has the answer' - its cognitively relaxing - i suggest we are too easily led to sudpend judgement on issues which entirely deserve our full consideration