Comment by mcguire

"Without individual lifetimes, you don’t need to write destructors, nor do your programs need to walk data structures at run time to take them apart."

Destructors are a very bad idea if you are using any form of garbage collection other than reference counting. The destructors won't run until some arbitrary time after the last access to the object, and in the case of arenas, what would be a very fast deallocation becomes proportional to the number of objects. Further, if destructors can revive objects, everything gets very complicated.