Tangled code is hard to read and hard to change.
Defects are hard to fix.
A fix to one defect often causes other defects.
New features are hard to add. When adding new features, one must “work around” the compromises of the past.
An upgrade to an operating system (even a service pack) may cause changes or failures to the tool.
Code that is specific to OS or processor or byte-alignment may fail on a later OS or processor or compiler.
Magic boxes are not truly magical. They are normal computers. Their magical aspect is the specific configuration that allows them to perform the tasks you need.
Not being truly magical, they suffer the same problems as regular (non-magical) computers. They are vulnerable to malware. File systems lose data. Disk drives fail. Memory errors occur.
When the magical box fails, your work stops. Perhaps not all of your work; perhaps only one or two tasks in a larger process. But the work performed by the magic box is necessary (otherwise you wouldn't be doing it) and can you deliver your product without that work?