Why is not deleting an object that has a destructor with a side effect undefined behavior in C++11?

Question

This answer quotes C++11 Standard 3.8:

if there is no explicit call to the destructor or if a delete-expression (5.3.5) is not used to release the sto

Answer 1

In this case, we do have a precise answer. The specific line was introduced to resolve CWG 1116, "Aliasing of union members".