What José Valim has done in building an entire community around elixir single-handedly is absolutely incredible. Numerical Elixir looks amazing as well.
José is an enormous asset to the community and has an influence on many of the marquee projects, but it definitely isn't single-handedly done. He cares about the ecosystem and is very generous with his time and attention.
Anecdotally speaking, he hasn't been hands on with Oban[1], yet he still offers advice and guidance around the project because it is in the Elixir community.