It's more than cheating; it's not taking responsibility for one's own safety, relying on others to help e.g. donate spare kit in the event of an accident, and not being in a position to stop and help others. See Welsh 3000 thread for similar comments.

Would those who avoid carrying kit go for a high level walk in the Lakes without? I doubt it, so what has changed just because they are in a race?

Selfish is another word that springs to mind.