Note that large amounts of OSS is used in companies, but it's generally code that developers are expected to know well enough to dive into if need be. And code that is popular enough to be well tested for bugs and known that breaking errors in the framework will get fixes. Examples would be things like Python or Node.js.
As a manager a potential problem you can have is a major bug your team is responsible for that no one is qualified to fix and thus your only reasonable time estimate is unknown. Avoiding certain parts of OSS is often a precaution against this situation.