Join selections are too trivial -- in real use cases you almost never only want to select a single property from a single node if you're joining.
e.g.
https://www.datastax.com/blog/gremlin-recipes-2-sql-gremlin # V JOIN translation
https://www.datastax.com/blog/gremlin-recipies-6-projection-selection # C. project(labels…).by(…)