Louis had gigantic and overly muscular shoulders, smaller chest comparitively. It's not about being in position TO punch, it's about being in position to deliver force, and both do that well-enough. But their postural limitations aren't on purpose. They have good posture for what their bodies are capable of. Both Louis and Golovkin compensate the same way, shifting forward further.
Louis Monaco is an interesting character. When he takes a beginning position, it's very good. But look what happens when he throws or has to defend a punch. The thing that's wrong isn't the straightness of his back, it's everything else. He LOOKS like a guy who knows how to LOOK like he knows how to fight, but doesn't. However, his whole career was defined by one moment, in a fight with Buster Douglas he accidentally hit Douglas after the bell, and Buster hit the ropes like he'd been shot in the face. The one thing Monaco could do, was hit very hard despite hit foot positioning being God awful.