The vastly more common use-case I've seen is when you want to have an optional value, but don't want the heap allocation that comes with std::unique_ptr. std::

The vastly more common use-case I've seen is when you want to have an optional value, but don't want the heap allocation that comes with std::unique_ptr. std::optional is an useful wrapper because a simple "bool + object" would call constructors and all when that might be undesirable. IMO, ternary logic belongs as an enum class, to require developers to be explicit about what branches are taken for what values.