The issues being discussed are not intellectual disagreements that had close to zero effect on the lives of the people involved, though.
Would you agree, that in a marriage, that money in a shared account is property owned by both husband and wife? And yet, because of the father's belief, he took the money out and converted them into gold without telling his wife. Is this a mere intellectual disagreement, or is this a physical betrayal rooted from his belief? The trust has been broken and the disagreement is no longer on purely hypothetical ground.
Realize that today the money became gold bars, next time the money might become a donation to a far-right group in Montana. Can the wife trust him after this?
Uh, no, it says that, e.g., for the wife it involved a significantly altered home life, spending, and stockpiling in the home on which she was not consulted and which her concerns about were ignored. And while it doesn't discuss the details of the impacts, treating the daughters sexual orientation as both a choice and a wrong choice is not a mere intellectual disagreement, and certainly did not have trivial impacts.
The only person who the "intellectual disagreement that has close to zero impact on [...] everyday life" description might even approximately work for (and even then it is a stretch) is the son, who...is the only one who didn't sever relations.
But you're right, saying it had zero impact is an exaggeration. It does seem like it had a small impact, at a minimum.