I suppose there are some developers who are not advanced enough to contribute to the project, but smart enough to use a framework? I don't know: Tom Dale did reply to the gist, and mentions there are non-trivial CS problems being solved.

Ember is actively trying to compete with angular (backed by google) and others - and I think the people rooting for ember are just people feeling let down after deciding to move forward on it in production.

edit: Tom's actual quote: "trying to solve are novel computer science problems"