I wholeheartedly agree. Note that my second example was exactly that type of interview - we leave the candidate to code alone, technically sometimes in the same room as us but sometimes in a separate room, but either way with only a few "check ins" every 15-45 minutes depending on how things go. They have internet access, a base file and console session open that can run the file, and an editor already set up (not necessarily their editor of choice, though we've had people install an editor at the start of this process).
In this scenario, having someone literally be unable, in 2 hours, to replicate the first example code of some library, when they have access to almost identical code in the docs, is a pretty good filter.
In this scenario, having someone literally be unable, in 2 hours, to replicate the first example code of some library, when they have access to almost identical code in the docs, is a pretty good filter.