I see nothing wrong with releasing an utterly bare-bones version, like the schema one he mentions, i.e. a MVP. Then, you polish over time. Even SO wasn't a SO clone at launch. (Of course, if someone promised a complete clone, that's foolish).

The big problem is that you can't get started on this upward curve, because no one will use it, since SO already exists and is far better. There's no oxygen.

[a different story if SO suddenly stopped meeting needs e.g. turned expertsexchange in cash-pursuit]