This is good to keep in mind for those of us obsessed with flat or curling irons and blow dryers and treatments. No matter how great your hair looks in the moment, there's bound to be some long-term damage if you overdo it — so at least use a heat protector (like this HSI one, $14.89 on Amazon).
I used my blow-dryer to style my hair almost daily even when it was bad, I was just mindful while using it. Plus, I love to curl or wave my hair. While there's definitely some breakage, it's nothing overt.
OFC, if you're using constant and high heat on really brittle hair, you may want to lay off. Plus, with air-drying curl enhancers ($36 on Hair Story), sea-salt sprays ($26.24 for a Bumble & Bumble version on Amazon), and restyling sprays ($44 on Amazon for Oribe's), you can ditch the heat dependency and really embrace your natural hair.
Final Thoughts: I mean, 100% yes, if you're curling or straightening your hair to the point where it's breaking, then avoid heat products. Otherwise, use them at your own discretion and comfort — with a touch of common sense.