My gut feeling is that a lot of issues in this class are because the allocator for STL containers are built into the container, rather than passed-in. So, rather than:
That's a different issue. Tangentially related that Allocator::construct has the same slightly crippled interface, so both the allocator concept and the container interfaces would needed to be fixed for accepting a lambda.
The stored allocator issue comes up when you need to store a bunch of vectors with the same stateful allocator, and you needlessly have to have a copy in each vector.
If every element of a vector can have its own allocator, and you later do
v.erase(v.end() - 1);
how would the vector know it has to call BobFree? The class _could_ store that with each element, but for small element sizes, that’s quite a bit of overhead.