It’s incredibly useful to be able to easily iterate over all possible values of a type at runtime or otherwise handle enum types as if they are their enum value and not just a leaky wrapper around an int.
If you let an enum be any old number or make the user implement that themselves, they also have to implement the enumeration of those numbers and any optimizations that you can unlock by explicitly knowing ahead of time what all possible values of a type are and how to quickly enumerate them.
What’s a better representation: letting an enum with two values be “1245927” or “0” or maybe even a float or a string whatever the programmer wants? Or, should they be 0 and 1 or directly compiled into the program on a way that allows the programmer to only ever need to think about the enum values and not the implementation?
IMO the first approach completely defeats the purpose of an enum. It’s supposed to be a union type, not a static set of values of any type. If I want the enum to be tagged or serializable to a string that should be implemented on top of the actual enumerable type.
They’re not mutually exclusive at all, it’s just that making enums “just tags” forces you to think about their internals even if you don’t need to serialize them and doesn’t give you enumerability, so why would I even use those enums at all when a string does the same thing with less jank?