Some languages have separate “value types” and “reference types” (https://en.wikipedia.org/wiki/Value_type_and_reference_type) exactly for that reason, with value types being copied when passed into or returned from a function, so they never get shared. That makes it easy to determine whether they can be stack allocated.

Intended use is to use value types for small immutable values (small because copying large objects is more costly, and immutable so that the copying doesn’t make a difference, semantically)

That can significantly decrease the number of garbage collected objects and with it memory usage (the smaller the object, the larger the relative overhead of a few bytes of data for use by the garbage collector)