Depression and anxiety do horrendous damage to cognition, scramble health, cost wages over time, and increase all-cause mortality. And a lot is driven by irrational thoughts.

That being said, imho there is absolute something there to the "too rational" bit. One gets really good at coming up with reasons something will not work. Negativity bias becomes overwhelming, and hope and optimism get swamped by a unproductive abundance of cynicism.