There was a much better article with a lot more detail written about this a few years back, but this article covers the general idea.
http://www.bettorstalk.com/index.php...view&id=40
It's much easier for a national operation to get even bets on both sides. A local bookie needs a deep bankroll for a season when your local favorite won't stop winning. In the long run, things will even out, but can you wait for the long run? And in Boston in 2004, where can you put the line and get a blanace of bets. Everyone wants to bet the Pats, if you set the line too high, they just won't bet.
You can say "I'll stop accepting bets on the heavy side", but when one of your regulars calls with a bet, are you really going to turn him down?
*** edited to add***
I didn't really think it through, but if you're the middle man, you're not on the hook for all that cash. Your concern is if the bookie you are middling skips out after a big game. You're on the hook then to your customers.
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