Physical tools change how ideas form. Paper and pen, a whiteboard, a printout with a marker: they slow the process down in a way that’s useful. When everything is on screen, iteration is cheap and the work can drift without friction. Working by hand introduces resistance. Mistakes can’t be undone, you have to cross out, redraw, reconsider, and that friction is part of the thinking. It also tells you something about the person you’re working with, whether they’re engaging in the [[Visual thinkers vs. visualisers]] sense or just representing what’s already decided.
[[Fat-marker method]] extends this: a tool that can’t produce fine detail forces the work to stay at the level of structure and flow. The physical constraint is protection against [[Stop spending time on wireframing]] territory, where the visual overwhelms the logic before the logic is settled.