IDer/Creationists, as well as other promoters of crankery, often ask why, when their lack of credentials in the fields they so ruthlessly criticize are called to bear, the same lack of credentials don't also apply to the defender of the consensus of scientific opinion. Shouldn't the burden be the same, with either credentials or lack thereof applying equally on both sides, fair and balanced and all that?
No. Life is rarely fair and balanced. Life is ruthlessly reality-oriented, and so is the scientific community. It's full of very brilliant people, with years of experience, and a genuine passion for what they do, pitted against each other in an arena that begs for critical attack, and rewards the victorious rebel with the status of legend. Consensus there happens rarely, and not without reason. To accept that takes mere acknowledgement. Challenging it, however, is going to take a good deal more. You're claiming you know better than all those people. It is the equivalent of claiming you can defeat the UFC Heavyweight champ. Yes, if you won't get in the ring with him, or do science like the scientist, your background is going to come into question a lot more than someone who grants their superiority.
I've never seen it put better than Mike Dunford does:
"Agreeing with the consensus in the other field is essentially a statement that you understand the current state of knowledge in that field, and are willing to extend the people who actually work in that area the courtesy of not thinking that they're all permanently out to lunch.
Disagreeing with the consensus sends an entirely different message. It says: 'I, Joe Blow, on the basis of my extensive experience as a toothbrush-bristle designer, think that I am better able to evaluate the scientific status of evolution than people who have spent a lifetime studying evolution.'"
It is, quite simply, arrogant in the extreme. Odd that it comes so often from people who greatly tout the value of modesty.