Why all-forward batteries complicate machinery layout

Why do all-forward designs struggle to place boilers and engines far enough aft?

The concentration of forward armament constrains the available internal arrangement; moving funnel and machinery spaces helps, but a real hull would need tailored changes.

The game constrains where boilers and engines can sit, which makes a forward concentration of heavy turrets difficult to balance. Moving the funnel aft creates room and lets the superstructure offset some of the forward battery's weight. The resulting arrangement still looks front-heavy because the fixed hull cannot be tailored around the machinery and magazines. A real design would probably modify the hull form instead of accepting the game model unchanged.