With RAII, it is trivial to move things from stack to heap, or to a member of something that might be on the stack or heap or in a container, without changing any of the code that implements the object. Most usually you don't need to declare or define any constructors, assignment operators, or a destructor; the compiler provides them, and guarantees they are correct. (Sometimes you provide one constructor as a convenience for users.)
It has been many years since I found a use for an abstract virtual base class.
Literally millions of people understand it all, and use it every day with no difficulty. You don't need to invent difficulties, or waste days "proofing" code that may be written exactly once and never touched again.
To clarify, I think by “move things from stack to heap” you mean “move values from stack to heap”, where, e.g., `std::vector<int>` is a value. The vector’s data is still on the heap (or in the allocator’s pool for `std::pmr::vector<int>`) but the value in the sense of value-semantics is moved from stack to heap.
It has been many years since I found a use for an abstract virtual base class.
Literally millions of people understand it all, and use it every day with no difficulty. You don't need to invent difficulties, or waste days "proofing" code that may be written exactly once and never touched again.