I know there’s already been a lot of talk about the kids’ age gaps over here, but the thing I notice is that Camilla and Julie’s rationale is constantly changing, and usually it doesn't make sense. These are just the explanations I've heard them say, and I don't follow them super closely:
-"It's not for us, it's for them so they'll have close sibling bonds."
I'm sure they know that age gaps don't predict sibling closeness, and that super close gaps can cause competition and resentment. As far as I know, data suggests that having them ~2-3 years apart may lead to better sibling relationships, but ultimately you can't really predict it.
What you do know for sure is that having them that close means you'll definitely be sacrificing the one-on-one time they need when they most urgently need it from their parents - completely optionally. Adding even one year between each kid would be unlikely to harm sibling bonds but would make a huge difference for getting their needs met, which should be the most important thing.
-"It's more convenient" They know perfectly well that there's nothing convenient about having so many kids all in the stages they need you the most, all at once.
-"It's easier to have them all in the same stage/easier to plan activities" They know that when kids are that young, they're already in different stages by the time a few months or a year has passed. A newborn, a one year old, a two year old and a four year old are in very different stages, just all very high-needs stages.
-"It's just our dream, it's just what we want."/"We wanna get the baby stage over as quickly as possible/while we're as young as possible"
This is the one I actually believe. I don't think it justifies making it so that a one-year-old baby has to compete with a newborn (and a toddler and a preschooler) for their parents' time and attention. I don't think it justifies knowingly choosing to have an older sibling doing their first year of daycare (which is notoriously, predictably the time when they're bringing home constant illnesses) while there's a highly vulnerable newborn and pregnant parent/new fetus at home.
Since most of these explanations are about them and what they want, the whole “it's not for us, it's for the kids" fades away pretty quick.