Yeah, I guess my comment was kind of off the cuff.
What I was thinking about, was that seatbelts are hardly "100% perfect in all scenarios." I mean, they can make it a more difficult to get out of a burning vehicle quickly, just as an example. Even ignoring the possibility of malfunction, or jamming and such, they're not perfect.
The fact is, even if seatbelts decrease your risk overall, they are nowhere near 100% perfect. Nevertheless, many of us choose to use seatbelts, and indeed even chose to do so before widespread legislation.