The downside is that when you “baby proof” things, you don’t actually make things “safer”. In fact, by NOT teaching your kid boundaries, you might actually prevent a lot of small accidents, but might indirectly CAUSE a really big accident.
Kids who grow up with more “street smarts”— lots of small injuries, but no major critical one which can cause death or other irreversible injuries.
Kids who grow up in a “safe environment”— no small injuries, but can perhaps die from a really major one.