Why is a liner brush useful for making long thin lines?

Correct answer: Its long bristles hold more paint for a continuous line

The governing concept is matching a brush’s structure with the required stroke. A liner brush has long, narrow bristles that can carry a small reservoir of paint and release it gradually while the hand moves. This supports a flowing, continuous thin line, such as a branch or decorative curve. Handle weight, absence of bristles and dry-paint-only use do not explain its function.