Not sure you are right about the linking part.
If I read it right, they are still using dynamic linking. So, if a module's Interfaces (input and output parameters) have not changed, the module that needs fixing can simply be replaced. So while it is technically a new version of the module, it can be accepted as a revised version of the original.
Your hairball scenario takes hold when these interfaces do change. Then, the changed module becomes a significantly different version of the module. The modules that need to call the new version must also be re-issued in new versions, etc. The caller modules that don't need the change could remain untouched and continue to call the old version of the module. Some of the memory savings that the DLL scheme has would evaporate, but it would still work.
In the case that a given module requires interface changes in a module that it calls, both the caller and the called module modules would need to be re-issued in a new versions. Depending on the nature of the problem, this may also develop into a hairball scenario. But, it need not necessarily.
It boils down to being damned sure you've got the interfaces right the first time.
