Indeed. In the case of self-referential borrows, this is not allowed because Rust wants copying structures byte-for-byte (e.g. `memcpy`) to always be safe.
The solution was `Pin<T>` et. al., which gives a way to make some value immovable in memory.
An equivalent yet simpler version of this system could be integrated into the borrow checker (this was a proposed solution for Rust), but as I said before, it would not be backwards-compatible, hence the need for `Pin`.
