But without the let, there's a warning. And culturally speaking, let _ is discouraged for this reason. If I want to ignore an error condition, I unwrap() instead, so at least my dumb decision will blow up in my face later instead of faint silently.
I think they were talking about the compiler-enforced exhaustive match, not must_use.
The fact that you must acknowledge the existence of the error value before accessing the meaty success value (either with a match, an unwrap, or a try) is a great feature in Rust.
must_use forcing you to handle errors for things you don't need the meaty success value of is just icing on the cake.
