Why should infographic say that? It characterised norms of one demographic in one time and place. It does not have to make rundown of everything.
Traditional alternative to nuclear family is extended family. Nuclear family as we know it is early 20 century norm, basically 1950 ideal.
Or Asian and old Eastern European arrangements where woman goes to live with husbands familly.
Interestingly, the different structure of black family (including supposed matriarchy, really) was blamed for social ills in black communities in 1965.
If the infographic covered all the possible human cultural arrangements wrt families, that part alone would be far longer than everything else in it. But the point here is not to educate about all possibilities - it's rather to point out that a specific arrangement is considered normative, and (perceived) adherence or non-adherence to it is used to establish a hierarchy of groups.
It could be, but I don't see the infographic saying that. The infographic could just as easily be saying that no family relationships at all is the (implied to be more desirable) alternative.
In fact, that's a big issue with the infographic as a whole: what alternatives are we supposed to compare all these things to? None are given.