why SOAP without WSDL?

Is there a good reason to deploy or consume a SOAP service without using a WSDL "file"?

Explanation:

I'm in a situation where a 3rd-party has created a SOAP service that does not follow the very WSDL file they have also created. I think I am forced to ignore the WSDL file in order to consume this service. Therefore I'm researching how to do this.

What I am really wondering is why it is even possible to do this? What is the intention?

Is it designed so that we can use poor services made by poor programmers? Surely there must be a better reason. I almost wish it wasn't possible. Then I could demand they write it properly.