Building on third party services is a brilliant, if not essential, part of the innovation process. The fact that people choose not to use the most third party service among content websites is their choice (and it's an understandable one), but they should learn to live with the consequences of that decision, which will include not being able to use some services they might want to.

Saying "It'd be better if content sites didn't use FB!" is something that would have a detrimental impact on the web experience of more than a billion other people who have chosen not to opt out. That's something that you have to consider when you suggest an alternative solution.