"Openness" is a relative and meaninglessly vague term in this context. Anything short of a open-sourced program and completely public data is less "open" than some alternative. The complaints that 99.99% of people make about APIs have less to do with "openness" than poor communication by the provider in the forms of bad documentation and unwarned changes.
TFA: "Facebook Connect is not open. It's controlled by one company."
Yes, because if it was another company, you wouldn't care about this API. The API only matters to anyone because it's Facebook.
I adore free software, but "openness" is a lousy justification for trying to work up umbrage about the difficulties of working in a parasitic developer ecosystem.