If A is std::allocator, then this will call placement new, as by ::new((void*)p) T(rv)(until C++20)std::construct_at(p, rv)(since C++20). This effectively requires T to be move constructible.
If std::allocator or a similar allocator is used, a class does not have to implement a move constructor to satisfy this type requirement: a copy constructor that takes a const T& argument can bind rvalue expressions. If a MoveInsertable class implements a move constructor, it may also implement move semantics to take advantage of the fact that the value of rv after construction is unspecified.
Although it is required that customized construct is used when constructing elements of std::basic_string until C++23, all implementations only used the default mechanism. The requirement is corrected by P1072R10 to match existing practice.