Yes, it could have security holes and it all needs to be reviewed. At scale, a lot of mistakes could pass code review. But people make mistakes, too. The code

Yes, it could have security holes and it all needs to be reviewed. At scale, a lot of mistakes could pass code review. But people make mistakes, too. The code that people write themselves or copy from Stack Overflow will have lots of bugs at scale. For the individual programmer who knows what they're doing and uses it responsibly, it's unclear that the risks are any higher than writing code on your own.