Why? Because it’s a lovely functional language with a nice, clean and easy syntax. Elixir is based on Erlang’s exceptional BEAM technology (highly concurrent virtual machine). Of course, it’s garbage-collected.
The essence of algorithm design is not to eliminate all error, but to make results robust in the face of error. Where de Havillands tried in vain to engineer a plane where the materials were strong enough to resist all cracks and fatigue, Boeing realized that the right approach was to engineer a design that allowed cracks, but kept them from propagating so far that they led to catastrophic failure. That is also Facebook’s challenge.