It works with anything, but yes, this reason make sense.

```irb
>> def foo(_)
>>   end
=> nil
>> foo 1
=> nil
>> foo 1, 2
ArgumentError: wrong number of arguments (2 for 1)
	from (irb):1:in `foo'
	from (irb):4
	from /opt/boxen/rbenv/versions/1.9.3-p545/bin/irb:12:in `<main>'
>> def foo(*_)
>>   end
=> nil
>> foo 1, 2
=> nil
```