If you test defensively[0], CI will catch the vast majority of functional bugs. Anything that is missed suggests at least two bugs: one in tests, and one in business logic.[0]

A reliable deployment pipeline is outside of CI, but can be kept straightforward and minimal to constrain the scope of failures.

Bugs happen, and systems complexify. It is possible to manage both of those risks down to near-zero by the time code reaches production release candidate stage.

In some industries, this is more important than others, though -- obviously the goal is to match quality to business needs.

But I agree with our thread predecessor: I haven't seen a broken build make it anywhere near production in many years, and it's not because of the snarky dismissal that provoked my original response.

[0] In some situations, proper tests are not possible, and in others they are not practical. And I acknowledge that I'm omitting things like visual design/layout bugs, which is probably not reasonable.