New std::map::erase() signature C++17

Question

According to this answer, an iterator must be implicitly convertible to const_iterator. Since that is true, as we can see happening in insert_or_assign(), then why in C++17 was a new signature added to std::map::erase()?

In C++11, we have iterator erase( const_iterator pos );

In C++17, we now have iterator erase( iterator pos );

Wasn't the C++11 signature good enough to receive iterator and const_iterator?

Answer 1

There's a potential ambiguity with erase(const key_type& key) when you pass an iterator. Consider the case where the key_type is something like std::any.