That commitment doesn't I clue staying in an unhappy marriage.
You are missing one huge problem- kids growing up in households where the parents are happy, know their parents aren't happy. That is toxicity all on its own. Often children in these households believe the 'staying for the children' line and it causes them guilt. The parents in the house start to resent each other, it's an awful atmosphere. An unhappy marriage is, more often than not, a toxic situation for kids to be in.
The whole 'staying together for the kids' is a lie people tell themselves. Happy kids don't grow up saying 'yeah my parents clearly were unhappy but we got to live in a huge house, that's what's important'. People who say this are staying for themselves because they choose to. But the 'staying for the kids' is a way to put a spin on it, appear selfless and victimise themselves. Its a choice to stay. And this choice is made for the adult, by the adult. Just the same as choosing divorce.
I don't think divorce is the ideal. And I don't believe anyone, especially with kids picks it lightly. And yes if patents can separate in a health way and live under the same roof, I think that's great. However it rarely works out like that. There's need to be clear responsibilities and both parties have to be completely on board.
When a relationship has got to the point you are considering divorce you are picking the lesser of 2 evils. Staying for will impact the kids. So will leaving.
I divorced. Moved to a smaller home. My eldest is an adult, well adjusted and happy. When we talk about divorce and marriage she believes me and her dad made the right choice. We aren't beasties. We are civil and work together if we need to for the kids.
My youngest is doing well at high school. Does well academically. Gets great reports on his behaviour, has friend and hobbies and is currently in the garden doing some pruning.
I am in no doubt that 2 separate happier households is better for my kids. The biggest problem with Divorce is when the adults put their needs, resentment, emotional lashing out in front of their children's well being. Which is the same as many couples who choose to 'stay together for the kids' do as well.