It promotes the idea of a magic number, and that hard work and time leads to returns (not true for the majority of startups). It encourages thinking like "Man I'm at the 950 hour mark, I'm almost there!", or even worse, planning one's product milestones around time spent.
He did not mean it that literally. He's proposing a rule of thumb.
He did not mean it that literally. He's proposing a rule of thumb.