I think the standards exist to assure safety, competence, and commitment to care. In that sense “all kinds of families” are not ok. Abusive families, neglectful families, probably families with untreated severe mental illness - not ok.
Someone adding children to a to a family to which they currently have no connection when that family does not have the time or space or resources to care for them - not ok.
but sizes and shapes and color and gender and marital status don’t mater to a kid at all compared to safety, love, security, support, belonging.... Heck, kids will chose love over safety every time.
love makes a family. Everything else is relative(s)