One implication of Tesler's law appears to be that it is impossible to increase the total complexity of a system. But this feels intuitively wrong to me after looking at the source code of any ERP project.
Maybe it only comes into play if you try to decrease over all complexity of a system. After a certain point complexity can't be reduced but can only be redistributed.
The Tesler conservation law is like first law of thermodynamics: you cannot destroy complexity, only change its form. Your observation is more like second law of thermodynamics: the complexity of a closed system always grows with time.
Maybe it only comes into play if you try to decrease over all complexity of a system. After a certain point complexity can't be reduced but can only be redistributed.