A student can learn to avoid mistakes so well that experimentation begins to feel dishonest.

Train someone to avoid errors and you can train them out of trying things. If every mistake carries a penalty, the safe move is to attempt only what you can already do, and experimenting starts to feel like a kind of cheating rather than like learning. The caution generalises well beyond the classroom.

Where you can, separate practice from assessment explicitly, so there is somewhere errors do not count. If you were taught this way, deliberately doing something badly, in low stakes, is worth practising as a skill. The discomfort is the old training rather than a real risk.