They are not harder to predict or control than garbage collection, and have the benefit of being completely deterministic. Of course you can always come up with some pathological case that would trigger a 'deallocation avalanche', but you would almost have to deliberately make an effort to run into a thing like that. And if you do, it's typically very easy to fix these kinds of things.

In the Objective-C era before automatic reference counting, you had these things called 'autorelease pools' which allow pretty straightforward control over deallocation. I think the same thing is still possible in ARC Obj-C and Swift.