I am into sailing and know a bunch of people that grew up “cruising the world” on sailboats with their parents. They’re almost all well adjusted, successful, and have unusually good social skills from learning how to make friends with people from other cultures. I think the structure and permanence that kids need is emotionally mature and available parents- the physical part is not the important part. Also, kids can have mental health problems and developmental disorders that have nothing to do with parenting- and it’s pretty awful to blame parents for their kids problems unless they intentionally abused them.