No, because RateLimiter is then copied on passing it around (pass by value).
That is problematic for two reasons: it might be a large type, so copying might be expensive. Second, more likely, it might violate invariants in your domain. For a rate limiter, this might mean accidentally copying around some internal state like a mutex, which then exists n times instead of 1 time, which can represent a problem (e.g. if you want to internally limit whole-app concurrency toward Redis).
I think the author can propagate RateLimiter instead of *RateLimiter, making it exactly the same
No, because RateLimiter is then copied on passing it around (pass by value).
That is problematic for two reasons: it might be a large type, so copying might be expensive. Second, more likely, it might violate invariants in your domain. For a rate limiter, this might mean accidentally copying around some internal state like a mutex, which then exists n times instead of 1 time, which can represent a problem (e.g. if you want to internally limit whole-app concurrency toward Redis).
You can see the code
Clearly is not large. Second the child object is a pointer so does not violate anything
And if if if... I am sure we can look for new constraints in any language
you still need to unpack that option somewhere.
_If_ you start out with an optional, and even then only once in the code path.