[erlang-questions] arity part of function name and variadic functions

[Peter Michaux]

I'm reading Joe Armstrong's "Programming Erlang: Software for a
Concurrent World". Two stand out features of Erlang are

  1) a function's arity is part of its name and
  2) there are no variadic functions.

What are the benefits of these two features from a language design perspective?

Were they concisely chosen to help the programmer in some way, were
they to make implementation easier or more efficient, or did they just
happen somewhere along the way?

Would the opposite choices have caused bad interaction with the
process-based concurrency model or some other part of the language?

Thanks,
Peter