This could be called map incompatibility, but the problem is far deeper.
In sophisticated programs, bugs are often covered by other bugs. This makes fixing a bug quite hard, because the fix seem to destroy a lot of other functionalities.
This is what happend in DK - using that option worked on vanilla DK, because pathfinding code had errors which were covering up the existing problems.
Also, there was no memory access control, so modules were able to write to a part of memory which they shouldn't have access to.