An interface is a library decision, not a language decision. The level of abstraction possible is part of a language decision. GP is saying that this adds "too

An interface is a library decision, not a language decision. The level of abstraction possible is part of a language decision. GP is saying that this adds "too much" possible abstraction, and therefore qualifies as "too high level". Another benchmark about "too high level" would be that it requires precisely the "guess the internal plumbing" tests that you describe. Not really advocating anything, just connecting the two a little better.