This is wholly unimaginative, there is a wide window of usage patterns that are not "unused or misused", for example, on by default but off with a project flag, or off when building a dev release but on when building a prod release, and also don't forget my point that many projects simply don't need the level of memory safety that rust provides. For example if you are single threaded and never free, or if you have an arena strategy.
Reducing concurrency and/or dynamic memory management makes a program easier to reason about for the compiler (and more likely to be correct in practice), not less in need of correct memory management.
I'm "wholly unimaginative" about what variables can be acceptably corrupted; I can only think of deliberately reading uninitialized memory as a randomness source, a case that is easier to prevent (by clearing allocated memory by default on the OS side) than to enable.
