You'd have to see the intersection in question to understand why. It's not a right-angle turn, there are a lot of cars coming the other way trying to make a right and edging into the street that I'm turning onto (even with a stream of traffic coming, and with a bike coming? Fair game, ya know)...suffice it to say that this is a case where staying to the far left and cutting the corner a bit is the best way to go.