Pushing the boundaries intentionally is good.

You learn and experiment, and you can judge the upside and the downside of pushing that boundary.

Pushing the boundaries accidentally is more likely to put you in danger without realizing it.

If you don't realize you're pushing the boundaries, and erroneously think you're safe, you're set up for a nasty surprise.

Systems should allow users to push boundaries intentionally but not lull them into doing it accidentally.