If you read at FR, then you're reading blog posts and articles from the MSM all the time; ergo, you're at risk of inadvertently consuming left-wing talking points. We're inundated with liberal views everywhere we turn, and much of it is insidiously subliminal.
What's especially harmful, is when posters who claim to be conservatives begin parroting those left-wing talking points in overt fashion on the forum. It's all too easy for others to fall for, when they believe it's coming from one of their own.
One thing I learned by being Mormon and leaving, was to think for myself and assume everyone is lying. Verify EVERYTHING as much as possible.
As a professional Historian, it is an automatic occupational hazard to look for bias and analyze things that way.
What is worse, IMO, is when people who claim to be conservative use the trust on these forums to deliberately slander others.