It’s more than just the cul-de-sac. Look at Bose’s comment above about being blocked from the shopping center by everyone having their own fenced in yards. Even if it’s a straight street, adding yards just increases distance and spreads things out further requiring cars.

It doesn't. What a cul-de-sac gives you is assurance that there is no noisy/dangerous traffic by your house at all hours. A street that a bus can serve is also a street where lots of cars will be going by (or at least want to go by even if not allowed)