Countable atomic structures are homogeneous, i.e., all finite tuple of the same first-order type are conjugate under automorphisms. While this is classical, I can't think of an example of a countable structure whose homogeneity is best proved via atomicity. Competing proof strategies include construction of that structure as a Fraisse limit possibly in an expanded language.
Is there a countable structure whose homogeneity is proved via atomicity in a manner at least as good (whatever that means) as via Fraisse theory?