I think the author of the article just haven’t understood how to use the ? operator yet, and don’t think they deserve being called “utterly incompetent” for it. Whether something is a monad or not is not necessarily something a programmer should have to think about on a daily basis IMO.
I just think of rust errors as a tagged enum with either a value or an error. And the ? operator as syntax sugar for returning if something was an error. IMO that simple understanding is sufficient to do error handling in Rust. I don’t think we should gatekeep programming behind some intellectual barrier of whether or not you understand category theory. I certainly don’t understand what a monad is, but I can still write working software and do error handling without unwraps.
Wrapping a value in a mutex just makes sense. After learning a bit of Rust I made a similar mutex wrapper in C++ when I had to protect a class member in a C++ project. I just had to change the type in the declaration, and bam the compiler tells me about all places this member was accessed. Much easier than using some buggy ‘find all references’, potentially forgetting a few places.