Agreed. I'm generally a believer in applications being "strict in what they emit, and liberal in what they accept" which seems to be what this guy is advocating

Agreed. I'm generally a believer in applications being "strict in what they emit, and liberal in what they accept" which seems to be what this guy is advocating. However, after reading it, I immediately equated this with an XSS attack and was re-evaluating the benefits of the strictness-always approach.