It is a dependency hell, ready to fire at the moment one of the packages changes its interface (API, behaviour, file layout, ...) recursively breaking a fractio

It is a dependency hell, ready to fire at the moment one of the packages changes its interface (API, behaviour, file layout, ...) recursively breaking a fraction of its dependents. Then you end up with multiple versions of the same package, versioned libraries, private copies of libraries and tools, and so on. Reuse works great on a small scale, but otherwise requires a lot of discipline both from the provider (who must refrain from interface changes, or have support for multiple versions from day one), and the consumer (who should be very considerate on which packages and features he uses).