Wobble extensions. U-joints. A flex-head ratchet I paid real money for. If it promised access, it was in my drawer. They all fail the same way: they trade torque for angle, and every one still needs swing room at the handle.
A chain drive is a different mechanism, not a better version of the same one. Inside the rigid body, a sealed steel roller chain runs between two sprockets, the same drive principle that puts engine power to a motorcycle's rear wheel. Chains don't flex under load. They lock and carry.
Angle tools redirect your pull and lose some of it at every joint. A rigid chain drive relocates your pull: 1:1, nothing lost to flex, rated 53 ft·lb (72 Nm), and it works in both directions.