Well it still is confusing.

That sounds to me like you agree that such "lesser code paths" like the stubs in Term::ReadLine are problematic ;-)

overload ... So it's possible to work with lesser code.

I don't think that's the same thing. The option fallback could have been given a better name, since what is's actually controlling is "magic autogeneration", and the operations it generates oftentimes Do The Right Thing. Plus, it has nothing to do with dependencies.

I don't think they translate well to Perl, that's mainly "Meta Programming" in Perl.

Yes, I think there are quite a few of these concepts that we don't see too much of in the Perl world. Although I haven't used it myself, my understanding is that Bread::Board is a Perl implementation of some of these concepts.

It's not up to the test suite to install the plugin it has to react to the given environment.

Well no, but my points above still stand: summarized, I personally think it's better if the module's behavior and tests are as deterministic as possible, instead of depending on whether or not a module is installed in the user's environment.