STM and message parsing do require the low level primitives: CAS (CompareAndSet/Swap), LL/SC (Load linked/store conditional).

Morealso STM doesn't solve the transactional problem that you face with using locks (mutex). Overall STM is just a fancy thing to have but hardly solves the big problem of transaction boundaries.

Message passing is easier to reason about due to global ordering but then you need some FIFO queues that are built upon some kind of mutex or spin lock... or Lamport based one (using for single producer-> single consumer one)... or some variant of Michael & Scott queue, etc.

In the end underneath you have to do the metal, so they cannot be 'considered harmful'.