Of course everything you've said is true. Nobody critical of divorce is saying, "it's the literal divorce that's bad for kids and as long as you just stay together and change none of the behaviors that lead to divorce, then that's better than getting a divorce."

But on the other hand, upper-middle-class Hacker Newsers who got divorced because they were "unfulfilled" probably shouldn't point to extreme cases of abuse and neglect to justify their decision, either.

All things being equal, people in this latter category should try to work it out. (Nobody disputes that there are extreme environments for which divorce is the only option.)

Finally, as always, we are talking about averages. Sociology doesn't have a proof-by-counterexample. If I say, "poverty leads to worse outcomes for kids" it's not a legitimate response to say, "there are some wealthy kids who do bad and some poor kids who do well, so you're wrong."

We're always talking about averages.