Not to mention, introducing all the permutations of methods as separate interfaces on the "consumer side" means extreme combinatorial explosion of interfaces. It is far better to judge the most common patterns and make single-method interfaces for these on the provider side.

Lots of such frequently-quoted Go "principles" are invalid and are regularly broken within the standard library and many popular Go projects. And if you point them out, you will be snootily advised by the Go gurus on /r/golang or even here on HN that every principle has exceptions. (Even if there are tens of thousands of such exceptions).