I think you are missing the whole point of CI. It has nothing to do with detecting if you are a poor coder (though it will do that too). CI catches issues in the working of multiple components together in your app, presumably coded by different people, possibly but not necessarily geographically apart, as fast as possible - hence the continuous. The key point is integration - there might be issues that your unit tests that you run before pushing the code won't catch, which CI will.

I would go out on a limb and say that the dev teams you have worked with have cultural issues about openness and saving face, and/or you have not worked on big enough (in terms of devs, LOC, distributed-ness) codebases. I might be wrong.