Earlier you wrote "Let's invent a new programming language that tells its users that the amount of time for which they hold memory should be "reasonable", without getting into specifics."
"Objects are never explicitly destroyed; however, when they become unreachable they may be garbage-collected. An implementation is allowed to postpone garbage collection or omit it altogether — it is a matter of implementation quality how garbage collection is implemented, as long as no objects are collected that are still reachable."
That subjective language specification is quite different than its objective implementation in a Python implementation, which appear to be what you refer to now.
This is essentially what Python-the-language does. It does not require reference counting, or mark-sweep, or any garbage collection at all. The language specification says at https://docs.python.org/3/reference/datamodel.html#objects-v... :
"Objects are never explicitly destroyed; however, when they become unreachable they may be garbage-collected. An implementation is allowed to postpone garbage collection or omit it altogether — it is a matter of implementation quality how garbage collection is implemented, as long as no objects are collected that are still reachable."
That subjective language specification is quite different than its objective implementation in a Python implementation, which appear to be what you refer to now.