Oh heck no.
The idea of a balance transfer is that new buisness is added to a lenders portfolio while taking it from the previous lender. In exchange they generally set the intrest rate at 0% for some time. It would be counterintuitive to allow for a lenders existing balances that might be racking up 10-30% to go to 0% just because you got approved for a new card. Can you imagine how many people would abuse that loophole if it existed to never get charged intrest?
Oh, wow...
I finally understand balance transfers. Even if the new lender never makes any interest off of the transferred amount, neither does the old lender. Genius!
I finally understand balance transfers. Even if the new lender never makes any interest off of the transferred amount, neither does the old lender. Genius!
It's a little more nuanced than that. 
Most people who carry balances long term won't pay off a balance transfer when the promotional period ends, then they get to pay the full APR to the new lender. Also most consumers only have a few cards and keep them for a long time so it's an incentive to obtain new customers.
K-in-Boston is correct but is leaving a small amount out. With a balance transfer you get a balance transfer fee. This is $0-10 or 0-4% whichever is higher with most banks picking $5 or 3% whichever is higher. Now the new bank is in that case making massive killing since you are providing those funds in advance and their US tresury lending rate is ~0.65%APY. Lenders are now getting a customer in to their system(account setup), making profit(BT fee), securing future profit potentual(unpaid amounts at end of promo/new charges).