what is the point of return in Ruby?

return allows you to break out early:

def write_code(number_of_errors)
  return "No problem" if number_of_errors == 0
  badness = compute_badness(number_of_errors)
  "WHAT?!  Badness = #{badness}."
end

If number_of_errors == 0, then "No problem" will be returned immediately. At the end of a method, though, it’s unnecessary, as you observed.

Edit: To demonstrate that return exits immediately, consider this function:

def last_name(name)
  return nil unless name
  name.split(/\s+/)[-1]
end

If you call this function as last_name("Antal S-Z"), it will return "S-Z". If you call it as last_name(nil), it returns nil. If return didn’t abort immediately, it would try to execute nil.split(/\s+/)[-1], which would throw an error.