I think that may be anecdotal hyperbole. Can you show me one congregation in the nation that has substituted Rick Warren's book for the Bible? Nearly every church has a web site. If what you said has any truth to it, then surely you can find one.
I'm not talking about officially. I'm talking about excitement. In my own church even the Bible is often so weakly translated, like in The Message version or Living Bible, that it's lost its impact. And quotes from the Warren books begin to replace scripture in the bulletins. Christians used to be excited about their own discoveries in the Bible. Now, they rarely make discoveries in the Bible unless they are directed by a Christian expert or popular speaker.
You know as well as I do that naysayers don't have to be overly logical or accurate!