Fortunately in this year 2015 we have a thing called hyperlinks via which evidence for assertions can be easily provided. If you treat op-eds from ‘unreliable’ sources as unreliable, fine. If you refuse to even check well-cited articles from ‘unreliable’ sources, you’re probably more interested in ideological correctness than truth.
A particularly irritating bugbear in informal, online discussions is the demand for sources for everything. Not only are people allowed to discuss things from memory or their own experiences, but when sourced, there is no requirement that those sources hew to any specific ideological bent.
More irritating is the rejection of sources when provided. Hacker News user pkinsky echoes my thoughts here.