Toxicity is important too

I would agree with your sentiment but not the choice of words...

I would replace toxicity with hardship...

hardships built character and hopefully a person develops resilience as a result

Quote from Quaintrelle

Nah- not toxicity

Criticisms, clashing opinions, discussions, sadness all those CAN happen without resulting to toxic behavior

This. Toxicity isn't healthy. Discourse, disagreements, and knowing that life and plans won't always go according to plan is. It's true you can't understand what is happiness and joy if you haven't experienced misery and sadness, but it doesn't mean toxicity is good for anyone. Too much negativity is dangerous to your mental health.