I agree, that was an asinine reponse from the bike shop clerk. But as others have said, some shops simply arent very good.

Personally as much as I would love to support the local shops near me, I rarely go in them. It's simply SO much cheaper (and often easier) to buy online if you know what you need.

Of course as another poster pointed out, you can make mistakes too and have to order things mulitple times to get it right. Something I've never, ever done..ever!