(This is one of a series of Software Engineering Maxims Which May or May Not Be True, developed over the last few years of working at Google. Your mileage may vary. Use only as directed. Past performance is not a predictor of future results. Etc.)
There is a peculiar dynamic when systems contain a mix of modules with very good monitoring along with modules with very poor monitoring; the modules with good monitoring report all of the errors.
The peculiarity becomes damaging if the result is to have all of the bugs filed against the components with good monitoring. It makes it look like those modules are full of bugs, when the reality is likely the opposite.