Comment by tialaramex

Universal Function Call Syntax goes both ways, Rust only offers to treat all of the things that seem like "methods" as free functions but not the reverse.

Under UFCS I could extend your Rust type by simply writing a new free function which matches the type, and this is in fact deliberately forbidden. (I can write the free function, but, doing so does not extend the type and I can't call it using the "method" syntax).