There are some tests where you’re right, but often the tricky part is shrinking failing cases. If you only want to generate sequences of state transitions that are considered “valid” then you typically have to have some sort of model state that dictates which test steps are valid for a given state, and you need to make sure that you don’t remove test steps during shrinking in a way that triggers a spurious failure by violating the preconditions that you followed to generate each step originally.

If any operation is valid in any state and you just want a totally random sequence of arbitrary operations, then yeah a stateful proptest framework may be overkill. But if you need to maintain a model state and specify preconditions for different operations, having a dedicated framework saves a lot of work.

I wrote a blog post about this stuff last year, if you’re interested in some more in-depth examples: https://readyset.io/blog/stateful-property-testing-in-rust

Also, as others have mentioned, parallel state machine testing is another really cool benefit you can get from having a dedicated framework, but it’s not the only benefit.