Are questions about interfaces/protocols and APIs on-topic for Code Review? 

And when I say "protocol", I mean this in the Objective-C/Swift (and potentially other languages) version of the word, which is basically the same as a Java interface.

There is this meta discussion: [“Code not yet written” clarification: Are unimplemented interfaces on- or off-topic?](https://codereview.meta.stackexchange.com/questions/2289/code-not-yet-written-clarification-are-unimplemented-interfaces-on-or-off-to), to which two moderators posted answers basically agreeing that the specific question which prompted that meta question is off-topic. 

However, there exists this meta discussion: [Are questions about public interface (API) on topic?](https://codereview.meta.stackexchange.com/questions/502/are-questions-about-public-interface-api-on-topic) which suggests that questions about APIs would be on-topic based on the existing accepted and highest upvoted answer.

I understand that APIs and interfaces are slightly different, but they're similar enough that I don't understand why a distinction would be drawn between the two (in terms of whether they're on-topic or not).

Moreover, there exists this seemingly very good question: [DataLayer Interfaces Genericized](https://codereview.stackexchange.com/questions/46194/datalayer-interfaces-genericized), which is purely about interfaces, something which the moderators have suggested would be off-topic, yet the question has 10 upvotes, and an accepted answer with 7 upvotes. Moreover, it has 0 votes to close, nevermind the close action of a moderator.