That distinction matters. Children can usually sense whether a no is grounded in reason or in anger. When it is thoughtful and consistent, it becomes easier to trust. Over time, children begin to understand that limits are part of love, not the absence of it.
And that may be the deepest lesson of all. A parent does not strengthen a child by protecting them from every difficult feeling. They strengthen them by helping them move through those feelings without fear. The child learns that disappointment is not defeat, that frustration can be managed, and that self-control is something worth building.