As the article points out, all major memcpy implementations already do this check inside memcpy. Sure, the caller can also check, but given that it's both redun

As the article points out, all major memcpy implementations already do this check inside memcpy. Sure, the caller can also check, but given that it's both redundant in practice and makes some common patterns harder to use than they would otherwise be, there's no reason to not just standardize what's already happening anyway and make everyone's lives easier in the process.