It's very common to have breaking changes that you need to carefully manage in a company's internal code, and where managing that as a full-on deprecation isn't worth the effort. Moving faster is often the better choice compared to never refactoring and improving the codebase.
I'm talking about internal libraries of a company, where there is no proven library with a stable interface as it's continuously evolving - similar to a young library in the OSS world that has no reasonable substitute. It might be something like a new parameter to a function, or an additional method call you need to make in a given version.
Applications that are written specifically in order to be run on the servers of a given company instead of being written to be general purpose have vastly different tradeoffs involved when it comes to choosing dependencies.
